| uncommas | Database.Esqueleto.Internal.Internal | 
| uncommas' | Database.Esqueleto.Internal.Internal | 
| unDBName | Database.Esqueleto.Internal.Internal | 
| unescapedColumnNames | Database.Esqueleto.Internal.Internal | 
| UnexpectedCaseErr | Database.Esqueleto.Internal.Internal | 
| UnexpectedCaseError | Database.Esqueleto.Internal.Internal | 
| UnexpectedValueError | Database.Esqueleto.Internal.Internal | 
| unFrom | Database.Esqueleto.Experimental.From, Database.Esqueleto.Experimental | 
| Union |  | 
| 1 (Type/Class) | Database.Esqueleto.Experimental.From.SqlSetOperation, Database.Esqueleto.Experimental | 
| 2 (Data Constructor) | Database.Esqueleto.Experimental.From.SqlSetOperation, Database.Esqueleto.Experimental | 
| UnionAll |  | 
| 1 (Type/Class) | Database.Esqueleto.Experimental.From.SqlSetOperation, Database.Esqueleto.Experimental | 
| 2 (Data Constructor) | Database.Esqueleto.Experimental.From.SqlSetOperation, Database.Esqueleto.Experimental | 
| UnionAll_ | Database.Esqueleto.Experimental.From.SqlSetOperation | 
| unionAll_ | Database.Esqueleto.Experimental.From.SqlSetOperation, Database.Esqueleto.Experimental | 
| UnionKind |  | 
| 1 (Type/Class) | Database.Esqueleto.Experimental.From.CommonTableExpression | 
| 2 (Data Constructor) | Database.Esqueleto.Experimental.From.CommonTableExpression | 
| Union_ | Database.Esqueleto.Experimental.From.SqlSetOperation | 
| union_ | Database.Esqueleto.Experimental.From.SqlSetOperation, Database.Esqueleto.Experimental | 
| Unique | Database.Esqueleto.Experimental, Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto.Legacy, Database.Esqueleto, Database.Esqueleto | 
| uniqueAttrs | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| uniqueDBName | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| UniqueDef |  | 
| 1 (Data Constructor) | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| 2 (Type/Class) | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| uniqueFields | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| uniqueHaskell | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| unJSONB | Database.Esqueleto.PostgreSQL.JSON | 
| unQ | Database.Esqueleto.Internal.Internal | 
| unsafeSqlAggregateFunction | Database.Esqueleto.PostgreSQL | 
| unsafeSqlBinOp | Database.Esqueleto.Internal.Internal | 
| unsafeSqlBinOpComposite | Database.Esqueleto.Internal.Internal | 
| unsafeSqlCase | Database.Esqueleto.Internal.Internal | 
| UnsafeSqlCaseError | Database.Esqueleto.Internal.Internal | 
| unsafeSqlCastAs | Database.Esqueleto.Internal.Internal | 
| unsafeSqlEntity | Database.Esqueleto.Internal.Internal | 
| unsafeSqlExtractSubField | Database.Esqueleto.Internal.Internal | 
| unsafeSqlFunction | Database.Esqueleto.Internal.Internal | 
| UnsafeSqlFunctionArgument | Database.Esqueleto.Internal.Internal | 
| unsafeSqlFunctionParens | Database.Esqueleto.Internal.Internal | 
| unsafeSqlValue | Database.Esqueleto.Internal.Internal | 
| unSingle | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| unSqlBackendKey | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| unSqlReadBackendKey | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| unSqlSetOperation | Database.Esqueleto.Experimental.From.SqlSetOperation | 
| unSqlWriteBackendKey | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| UnsupportedSqlInsertIntoType | Database.Esqueleto.Internal.Internal | 
| unUnionKind | Database.Esqueleto.Experimental.From.CommonTableExpression | 
| unValue | Database.Esqueleto.Internal.Internal, Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| UPDATE | Database.Esqueleto.Internal.Internal | 
| Update | Database.Esqueleto.Internal.Internal | 
| update | Database.Esqueleto.Internal.Internal, Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| updateCount | Database.Esqueleto.Internal.Internal, Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| UpdateException | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| updateGet | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| updateWhere | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| upper_ | Database.Esqueleto.Internal.Internal, Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| upsert |  | 
| 1 (Function) | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| 2 (Function) | Database.Esqueleto.PostgreSQL | 
| upsertBy |  | 
| 1 (Function) | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| 2 (Function) | Database.Esqueleto.PostgreSQL | 
| UpsertError | Database.Esqueleto.Experimental, Database.Esqueleto.Legacy, Database.Esqueleto | 
| useIdent | Database.Esqueleto.Internal.Internal |