Squeal.PostgreSQL.Definition

Squeal data definition language.

Definition

newtype Definition (schema0 :: TablesType) (schema1 :: TablesType)

A Definition is a statement that changes the schema of the database, like a createTable, dropTable, or alterTable command. Definitions may be composed using the >>> operator.

Constructors

UnsafeDefinition

Fields

• renderDefinition :: ByteString

Instances

Category TablesType Definition

Methods

id :: cat a a

(.) :: cat b c -> cat a b -> cat a c

Eq (Definition schema0 schema1)

Methods

(==) :: Definition schema0 schema1 -> Definition schema0 schema1 -> Bool

(/=) :: Definition schema0 schema1 -> Definition schema0 schema1 -> Bool

Ord (Definition schema0 schema1)

Methods

compare :: Definition schema0 schema1 -> Definition schema0 schema1 -> Ordering

(<) :: Definition schema0 schema1 -> Definition schema0 schema1 -> Bool

(<=) :: Definition schema0 schema1 -> Definition schema0 schema1 -> Bool

(>) :: Definition schema0 schema1 -> Definition schema0 schema1 -> Bool

(>=) :: Definition schema0 schema1 -> Definition schema0 schema1 -> Bool

max :: Definition schema0 schema1 -> Definition schema0 schema1 -> Definition schema0 schema1

min :: Definition schema0 schema1 -> Definition schema0 schema1 -> Definition schema0 schema1

Show (Definition schema0 schema1)

Methods

showsPrec :: Int -> Definition schema0 schema1 -> ShowS

show :: Definition schema0 schema1 -> String

showList :: [Definition schema0 schema1] -> ShowS

Generic (Definition schema0 schema1)

Associated Types

type Rep (Definition schema0 schema1) :: * -> *

Methods

from :: Definition schema0 schema1 -> Rep (Definition schema0 schema1) x

to :: Rep (Definition schema0 schema1) x -> Definition schema0 schema1

NFData (Definition schema0 schema1)

Methods

rnf :: Definition schema0 schema1 -> ()

type Rep (Definition schema0 schema1)

type Rep (Definition schema0 schema1) = D1 * (MetaData "Definition" "Squeal.PostgreSQL.Definition" "squeal-postgresql-0.1.1.4-k5IDJoGvjq2Crr3wWyEON" True) (C1 * (MetaCons "UnsafeDefinition" PrefixI True) (S1 * (MetaSel (Just Symbol "renderDefinition") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 * ByteString)))

(>>>) :: Category k cat => cat a b -> cat b c -> cat a c infixr 1

Left-to-right composition

Create

createTable

Arguments

:: (KnownSymbol table, SListI columns)

=> Alias table

the name of the table to add

-> NP (Aliased TypeExpression) (column ': columns)

the names and datatype of each column

-> [TableConstraint schema (column ': columns)]

constraints that must hold for the table

-> Definition schema (Create table (column ': columns) schema)

createTable adds a table to the schema.

>>> :set -XOverloadedLabels
>>> :{
renderDefinition $
  createTable #tab (int `As` #a :* real `As` #b :* Nil) []
:}
"CREATE TABLE tab (a int, b real);"

newtype TableConstraint (schema :: TablesType) (columns :: ColumnsType)

Data types are a way to limit the kind of data that can be stored in a table. For many applications, however, the constraint they provide is too coarse. For example, a column containing a product price should probably only accept positive values. But there is no standard data type that accepts only positive numbers. Another issue is that you might want to constrain column data with respect to other columns or rows. For example, in a table containing product information, there should be only one row for each product number. TableConstraints give you as much control over the data in your tables as you wish. If a user attempts to store data in a column that would violate a constraint, an error is raised. This applies even if the value came from the default value definition.

Constructors

UnsafeTableConstraint

Fields

• renderTableConstraint :: ByteString

Instances

Eq (TableConstraint schema columns)

Methods

(==) :: TableConstraint schema columns -> TableConstraint schema columns -> Bool

(/=) :: TableConstraint schema columns -> TableConstraint schema columns -> Bool

Ord (TableConstraint schema columns)

Methods

compare :: TableConstraint schema columns -> TableConstraint schema columns -> Ordering

(<) :: TableConstraint schema columns -> TableConstraint schema columns -> Bool

(<=) :: TableConstraint schema columns -> TableConstraint schema columns -> Bool

(>) :: TableConstraint schema columns -> TableConstraint schema columns -> Bool

(>=) :: TableConstraint schema columns -> TableConstraint schema columns -> Bool

max :: TableConstraint schema columns -> TableConstraint schema columns -> TableConstraint schema columns

min :: TableConstraint schema columns -> TableConstraint schema columns -> TableConstraint schema columns

Show (TableConstraint schema columns)

Methods

showsPrec :: Int -> TableConstraint schema columns -> ShowS

show :: TableConstraint schema columns -> String

showList :: [TableConstraint schema columns] -> ShowS

Generic (TableConstraint schema columns)

Associated Types

type Rep (TableConstraint schema columns) :: * -> *

Methods

from :: TableConstraint schema columns -> Rep (TableConstraint schema columns) x

to :: Rep (TableConstraint schema columns) x -> TableConstraint schema columns

NFData (TableConstraint schema columns)

Methods

rnf :: TableConstraint schema columns -> ()

type Rep (TableConstraint schema columns)

type Rep (TableConstraint schema columns) = D1 * (MetaData "TableConstraint" "Squeal.PostgreSQL.Definition" "squeal-postgresql-0.1.1.4-k5IDJoGvjq2Crr3wWyEON" True) (C1 * (MetaCons "UnsafeTableConstraint" PrefixI True) (S1 * (MetaSel (Just Symbol "renderTableConstraint") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 * ByteString)))

check

Arguments

:: Condition '[table ::: columns] Ungrouped '[]

condition to check

-> TableConstraint schema columns

A check constraint is the most generic TableConstraint type. It allows you to specify that the value in a certain column must satisfy a Boolean (truth-value) expression.

>>> :{
renderDefinition $
  createTable #tab
    ( (int & notNull) `As` #a :*
      (int & notNull) `As` #b :* Nil )
    [ check (#a .> #b) ]
:}
"CREATE TABLE tab (a int NOT NULL, b int NOT NULL, CHECK ((a > b)));"

unique

Arguments

:: SListI subcolumns

=> NP (Column columns) subcolumns

unique column or group of columns

-> TableConstraint schema columns

A unique constraint ensure that the data contained in a column, or a group of columns, is unique among all the rows in the table.

>>> :{
renderDefinition $
  createTable #tab
    ( int `As` #a :*
      int `As` #b :* Nil )
    [ unique (Column #a :* Column #b :* Nil) ]
:}
"CREATE TABLE tab (a int, b int, UNIQUE (a, b));"

primaryKey

Arguments

:: (SListI subcolumns, AllNotNull subcolumns)

=> NP (Column columns) subcolumns

identifying column or group of columns

-> TableConstraint schema columns

A primaryKey constraint indicates that a column, or group of columns, can be used as a unique identifier for rows in the table. This requires that the values be both unique and not null.

>>> :{
renderDefinition $
  createTable #tab
    ( serial `As` #id :*
      (text & notNull) `As` #name :* Nil )
    [ primaryKey (Column #id :* Nil) ]
:}
"CREATE TABLE tab (id serial, name text NOT NULL, PRIMARY KEY (id));"

foreignKey

Arguments

:: (HasTable reftable schema refcolumns, SameTypes subcolumns refsubcolumns, AllNotNull subcolumns, SListI subcolumns, SListI refsubcolumns)

=> NP (Column columns) subcolumns

column or columns in the table

-> Alias reftable

reference table

-> NP (Column refcolumns) refsubcolumns

reference column or columns in the reference table

-> OnDeleteClause

what to do when reference is deleted

-> OnUpdateClause

what to do when reference is updated

-> TableConstraint schema columns

A foreignKey specifies that the values in a column (or a group of columns) must match the values appearing in some row of another table. We say this maintains the referential integrity between two related tables.

>>> :{
let
  definition :: Definition '[]
    '[ "users" :::
       '[ "id" ::: 'Optional ('NotNull 'PGint4)
        , "username" ::: 'Required ('NotNull 'PGtext)
        ]
     , "emails" :::
       '[ "id" ::: 'Optional ('NotNull 'PGint4)
        , "userid" ::: 'Required ('NotNull 'PGint4)
        , "email" ::: 'Required ('NotNull 'PGtext)
        ]
     ]
  definition =
    createTable #users
      (serial `As` #id :* (text & notNull) `As` #username :* Nil)
      [primaryKey (Column #id :* Nil)] >>>
    createTable #emails
      ( serial `As` #id :*
        (integer & notNull) `As` #userid :*
        (text & notNull) `As` #email :* Nil )
      [ primaryKey (Column #id :* Nil)
      , foreignKey (Column #userid :* Nil) #users (Column #id :* Nil)
        OnDeleteCascade OnUpdateRestrict
      ]
in renderDefinition definition
:}
"CREATE TABLE users (id serial, username text NOT NULL, PRIMARY KEY (id)); CREATE TABLE emails (id serial, userid integer NOT NULL, email text NOT NULL, PRIMARY KEY (id), FOREIGN KEY (userid) REFERENCES users (id) ON DELETE CASCADE ON UPDATE RESTRICT);"

data OnDeleteClause

OnDelete indicates what to do with rows that reference a deleted row.

Constructors

OnDeleteNoAction

if any referencing rows still exist when the constraint is checked, an error is raised

OnDeleteRestrict

prevents deletion of a referenced row

OnDeleteCascade

specifies that when a referenced row is deleted, row(s) referencing it should be automatically deleted as well

Instances

Eq OnDeleteClause

Methods

(==) :: OnDeleteClause -> OnDeleteClause -> Bool

(/=) :: OnDeleteClause -> OnDeleteClause -> Bool

Ord OnDeleteClause

Methods

compare :: OnDeleteClause -> OnDeleteClause -> Ordering

(<) :: OnDeleteClause -> OnDeleteClause -> Bool

(<=) :: OnDeleteClause -> OnDeleteClause -> Bool

(>) :: OnDeleteClause -> OnDeleteClause -> Bool

(>=) :: OnDeleteClause -> OnDeleteClause -> Bool

max :: OnDeleteClause -> OnDeleteClause -> OnDeleteClause

min :: OnDeleteClause -> OnDeleteClause -> OnDeleteClause

Show OnDeleteClause

Methods

showsPrec :: Int -> OnDeleteClause -> ShowS

show :: OnDeleteClause -> String

showList :: [OnDeleteClause] -> ShowS

Generic OnDeleteClause

Associated Types

type Rep OnDeleteClause :: * -> *

Methods

from :: OnDeleteClause -> Rep OnDeleteClause x

to :: Rep OnDeleteClause x -> OnDeleteClause

NFData OnDeleteClause

Methods

rnf :: OnDeleteClause -> ()

type Rep OnDeleteClause

type Rep OnDeleteClause = D1 * (MetaData "OnDeleteClause" "Squeal.PostgreSQL.Definition" "squeal-postgresql-0.1.1.4-k5IDJoGvjq2Crr3wWyEON" False) ((:+:) * (C1 * (MetaCons "OnDeleteNoAction" PrefixI False) (U1 *)) ((:+:) * (C1 * (MetaCons "OnDeleteRestrict" PrefixI False) (U1 *)) (C1 * (MetaCons "OnDeleteCascade" PrefixI False) (U1 *))))

renderOnDeleteClause :: OnDeleteClause -> ByteString

Render OnDeleteClause.

data OnUpdateClause

Analagous to OnDelete there is also OnUpdate which is invoked when a referenced column is changed (updated).

Constructors

OnUpdateNoAction

if any referencing rows has not changed when the constraint is checked, an error is raised

OnUpdateRestrict

prevents update of a referenced row

OnUpdateCascade

the updated values of the referenced column(s) should be copied into the referencing row(s)

Instances

Eq OnUpdateClause

Methods

(==) :: OnUpdateClause -> OnUpdateClause -> Bool

(/=) :: OnUpdateClause -> OnUpdateClause -> Bool

Ord OnUpdateClause

Methods

compare :: OnUpdateClause -> OnUpdateClause -> Ordering

(<) :: OnUpdateClause -> OnUpdateClause -> Bool

(<=) :: OnUpdateClause -> OnUpdateClause -> Bool

(>) :: OnUpdateClause -> OnUpdateClause -> Bool

(>=) :: OnUpdateClause -> OnUpdateClause -> Bool

max :: OnUpdateClause -> OnUpdateClause -> OnUpdateClause

min :: OnUpdateClause -> OnUpdateClause -> OnUpdateClause

Show OnUpdateClause

Methods

showsPrec :: Int -> OnUpdateClause -> ShowS

show :: OnUpdateClause -> String

showList :: [OnUpdateClause] -> ShowS

Generic OnUpdateClause

Associated Types

type Rep OnUpdateClause :: * -> *

Methods

from :: OnUpdateClause -> Rep OnUpdateClause x

to :: Rep OnUpdateClause x -> OnUpdateClause

NFData OnUpdateClause

Methods

rnf :: OnUpdateClause -> ()

type Rep OnUpdateClause

type Rep OnUpdateClause = D1 * (MetaData "OnUpdateClause" "Squeal.PostgreSQL.Definition" "squeal-postgresql-0.1.1.4-k5IDJoGvjq2Crr3wWyEON" False) ((:+:) * (C1 * (MetaCons "OnUpdateNoAction" PrefixI False) (U1 *)) ((:+:) * (C1 * (MetaCons "OnUpdateRestrict" PrefixI False) (U1 *)) (C1 * (MetaCons "OnUpdateCascade" PrefixI False) (U1 *))))

renderOnUpdateClause :: OnUpdateClause -> ByteString

Render OnUpdateClause.

Drop

dropTable

Arguments

:: KnownSymbol table

=> Alias table

table to remove

-> Definition schema (Drop table schema)

dropTable removes a table from the schema.

>>> renderDefinition $ dropTable #muh_table
"DROP TABLE muh_table;"

Alter

alterTable

Arguments

:: HasTable table schema columns0

=> Alias table

table to alter

-> AlterColumns columns0 columns1

alteration to perform

-> Definition schema (Alter table schema columns1)

alterTable changes the definition of a table from the schema.

alterTableRename

Arguments

:: (KnownSymbol table0, KnownSymbol table1)

=> Alias table0

table to rename

-> Alias table1

what to rename it

-> Definition schema (Rename table0 table1 schema)

alterTableRename changes the name of a table from the schema.

>>> renderDefinition $ alterTableRename #foo #bar
"ALTER TABLE foo RENAME TO bar;"

alterTableAddConstraint

Arguments

:: HasTable table schema columns

=> Alias table

table to constrain

-> TableConstraint schema columns

what constraint to add

-> Definition schema schema

An alterTableAddConstraint adds a table constraint.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col" ::: 'Required ('NotNull 'PGint4)]]
    '["tab" ::: '["col" ::: 'Required ('NotNull 'PGint4)]]
  definition = alterTableAddConstraint #tab (check (#col .> 0))
in renderDefinition definition
:}
"ALTER TABLE tab ADD CHECK ((col > 0));"

newtype AlterColumns (columns0 :: ColumnsType) (columns1 :: ColumnsType)

An AlterColumns describes the alteration to perform on the columns of a table.

Constructors

UnsafeAlterColumns

Fields

• renderAlterColumns :: ByteString

Instances

Eq (AlterColumns columns0 columns1)

Methods

(==) :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Bool

(/=) :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Bool

Ord (AlterColumns columns0 columns1)

Methods

compare :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Ordering

(<) :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Bool

(<=) :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Bool

(>) :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Bool

(>=) :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> Bool

max :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> AlterColumns columns0 columns1

min :: AlterColumns columns0 columns1 -> AlterColumns columns0 columns1 -> AlterColumns columns0 columns1

Show (AlterColumns columns0 columns1)

Methods

showsPrec :: Int -> AlterColumns columns0 columns1 -> ShowS

show :: AlterColumns columns0 columns1 -> String

showList :: [AlterColumns columns0 columns1] -> ShowS

Generic (AlterColumns columns0 columns1)

Associated Types

type Rep (AlterColumns columns0 columns1) :: * -> *

Methods

from :: AlterColumns columns0 columns1 -> Rep (AlterColumns columns0 columns1) x

to :: Rep (AlterColumns columns0 columns1) x -> AlterColumns columns0 columns1

NFData (AlterColumns columns0 columns1)

Methods

rnf :: AlterColumns columns0 columns1 -> ()

type Rep (AlterColumns columns0 columns1)

type Rep (AlterColumns columns0 columns1) = D1 * (MetaData "AlterColumns" "Squeal.PostgreSQL.Definition" "squeal-postgresql-0.1.1.4-k5IDJoGvjq2Crr3wWyEON" True) (C1 * (MetaCons "UnsafeAlterColumns" PrefixI True) (S1 * (MetaSel (Just Symbol "renderAlterColumns") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 * ByteString)))

addColumnDefault

Arguments

:: KnownSymbol column

=> Alias column

column to add

-> TypeExpression (Optional ty)

type of the new column

-> AlterColumns columns (Create column (Optional ty) columns)

An addColumnDefault adds a new Optional column. The new column is initially filled with whatever default value is given.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col1" ::: 'Required ('Null 'PGint4)]]
    '["tab" :::
       '[ "col1" ::: 'Required ('Null 'PGint4)
        , "col2" ::: 'Optional ('Null 'PGtext) ]]
  definition = alterTable #tab
    (addColumnDefault #col2 (text & default_ "foo"))
in renderDefinition definition
:}
"ALTER TABLE tab ADD COLUMN col2 text DEFAULT E'foo';"

addColumnNull

Arguments

:: KnownSymbol column

=> Alias column

column to add

-> TypeExpression (Required (Null ty))

type of the new column

-> AlterColumns columns (Create column (Required (Null ty)) columns)

An addColumnDefault adds a new Null column. The new column is initially filled with NULLs.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col1" ::: 'Required ('Null 'PGint4)]]
    '["tab" :::
       '[ "col1" ::: 'Required ('Null 'PGint4)
        , "col2" ::: 'Required ('Null 'PGtext) ]]
  definition = alterTable #tab (addColumnNull #col2 text)
in renderDefinition definition
:}
"ALTER TABLE tab ADD COLUMN col2 text;"

dropColumn

Arguments

:: KnownSymbol column

=> Alias column

column to remove

-> AlterColumns columns (Drop column columns)

A dropColumn removes a column. Whatever data was in the column disappears. Table constraints involving the column are dropped, too. However, if the column is referenced by a foreign key constraint of another table, PostgreSQL will not silently drop that constraint.

>>> :{
let
  definition :: Definition
    '["tab" :::
       '[ "col1" ::: 'Required ('Null 'PGint4)
        , "col2" ::: 'Required ('Null 'PGtext) ]]
    '["tab" ::: '["col1" ::: 'Required ('Null 'PGint4)]]
  definition = alterTable #tab (dropColumn #col2)
in renderDefinition definition
:}
"ALTER TABLE tab DROP COLUMN col2;"

dropColumnCascade

Arguments

:: KnownSymbol column

=> Alias column

column to remove

-> AlterColumns columns (Drop column columns)

Like dropColumn but authorizes dropping everything that depends on the column.

>>> :{
let
  definition :: Definition
    '["tab" :::
       '[ "col1" ::: 'Required ('Null 'PGint4)
        , "col2" ::: 'Required ('Null 'PGtext) ]]
    '["tab" ::: '["col1" ::: 'Required ('Null 'PGint4)]]
  definition = alterTable #tab (dropColumnCascade #col2)
in renderDefinition definition
:}
"ALTER TABLE tab DROP COLUMN col2 CASCADE;"

renameColumn :: (KnownSymbol column0, KnownSymbol column1) => Alias column0 -> Alias column1 -> AlterColumns columns (Rename column0 column1 columns)

A renameColumn renames a column.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["foo" ::: 'Required ('Null 'PGint4)]]
    '["tab" ::: '["bar" ::: 'Required ('Null 'PGint4)]]
  definition = alterTable #tab (renameColumn #foo #bar)
in renderDefinition definition
:}
"ALTER TABLE tab RENAME COLUMN foo TO bar;"

alterColumn

Arguments

:: (KnownSymbol column, HasColumn column columns ty0)

=> Alias column

column to alter

-> AlterColumn ty0 ty1

alteration to perform

-> AlterColumns columns (Alter column columns ty1)

An alterColumn alters a single column.

newtype AlterColumn (ty0 :: ColumnType) (ty1 :: ColumnType)

An AlterColumn describes the alteration to perform on a single column.

Constructors

UnsafeAlterColumn

Fields

• renderAlterColumn :: ByteString

Instances

Eq (AlterColumn ty0 ty1)

Methods

(==) :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Bool

(/=) :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Bool

Ord (AlterColumn ty0 ty1)

Methods

compare :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Ordering

(<) :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Bool

(<=) :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Bool

(>) :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Bool

(>=) :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> Bool

max :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> AlterColumn ty0 ty1

min :: AlterColumn ty0 ty1 -> AlterColumn ty0 ty1 -> AlterColumn ty0 ty1

Show (AlterColumn ty0 ty1)

Methods

showsPrec :: Int -> AlterColumn ty0 ty1 -> ShowS

show :: AlterColumn ty0 ty1 -> String

showList :: [AlterColumn ty0 ty1] -> ShowS

Generic (AlterColumn ty0 ty1)

Associated Types

type Rep (AlterColumn ty0 ty1) :: * -> *

Methods

from :: AlterColumn ty0 ty1 -> Rep (AlterColumn ty0 ty1) x

to :: Rep (AlterColumn ty0 ty1) x -> AlterColumn ty0 ty1

NFData (AlterColumn ty0 ty1)

Methods

rnf :: AlterColumn ty0 ty1 -> ()

type Rep (AlterColumn ty0 ty1)

type Rep (AlterColumn ty0 ty1) = D1 * (MetaData "AlterColumn" "Squeal.PostgreSQL.Definition" "squeal-postgresql-0.1.1.4-k5IDJoGvjq2Crr3wWyEON" True) (C1 * (MetaCons "UnsafeAlterColumn" PrefixI True) (S1 * (MetaSel (Just Symbol "renderAlterColumn") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 * ByteString)))

setDefault

Arguments

:: Expression '[] Ungrouped '[] (Required ty)

default value to set

-> AlterColumn (optionality ty) (Optional ty)

A setDefault sets a new default for a column. Note that this doesn't affect any existing rows in the table, it just changes the default for future insertTable and updateTable commands.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col" ::: 'Required ('Null 'PGint4)]]
    '["tab" ::: '["col" ::: 'Optional ('Null 'PGint4)]]
  definition = alterTable #tab (alterColumn #col (setDefault 5))
in renderDefinition definition
:}
"ALTER TABLE tab ALTER COLUMN col SET DEFAULT 5;"

dropDefault :: AlterColumn (optionality ty) (Required ty)

A dropDefault removes any default value for a column.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col" ::: 'Optional ('Null 'PGint4)]]
    '["tab" ::: '["col" ::: 'Required ('Null 'PGint4)]]
  definition = alterTable #tab (alterColumn #col dropDefault)
in renderDefinition definition
:}
"ALTER TABLE tab ALTER COLUMN col DROP DEFAULT;"

setNotNull :: AlterColumn (optionality (Null ty)) (optionality (NotNull ty))

A setNotNull adds a NOT NULL constraint to a column. The constraint will be checked immediately, so the table data must satisfy the constraint before it can be added.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col" ::: 'Required ('Null 'PGint4)]]
    '["tab" ::: '["col" ::: 'Required ('NotNull 'PGint4)]]
  definition = alterTable #tab (alterColumn #col setNotNull)
in renderDefinition definition
:}
"ALTER TABLE tab ALTER COLUMN col SET NOT NULL;"

dropNotNull :: AlterColumn (optionality (NotNull ty)) (optionality (Null ty))

A dropNotNull drops a NOT NULL constraint from a column.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col" ::: 'Required ('NotNull 'PGint4)]]
    '["tab" ::: '["col" ::: 'Required ('Null 'PGint4)]]
  definition = alterTable #tab (alterColumn #col dropNotNull)
in renderDefinition definition
:}
"ALTER TABLE tab ALTER COLUMN col DROP NOT NULL;"

alterType :: TypeExpression ty -> AlterColumn ty0 ty

An alterType converts a column to a different data type. This will succeed only if each existing entry in the column can be converted to the new type by an implicit cast.

>>> :{
let
  definition :: Definition
    '["tab" ::: '["col" ::: 'Required ('NotNull 'PGint4)]]
    '["tab" ::: '["col" ::: 'Required ('NotNull 'PGnumeric)]]
  definition =
    alterTable #tab (alterColumn #col (alterType (numeric & notNull)))
in renderDefinition definition
:}
"ALTER TABLE tab ALTER COLUMN col TYPE numeric NOT NULL;"