# CAST function and operator Returns the value converted to the specified type The `cast` function and operator return a value converted to the specified [type](../../types/). ## Signatures ```mzsql CAST ( AS ) ``` | Syntax element | Description | | --- | --- | | `` | Any value you want to convert. | | **AS** `` | The return value's [type](/sql/types/). | ```mzsql :: ``` | Syntax element | Description | | --- | --- | | `` | Any value you want to convert. | | `::` | The return value's [type](/sql/types/). | The following special syntax is permitted if _val_ is a string literal: ```mzsql '' ``` | Syntax element | Description | | --- | --- | | `` | The return value's [type](/sql/types/). | | `''` | A string literal value. This special syntax is permitted if `` is a string literal. | ### Return value `cast` returns the value with the type specified by the _type_ parameter. ## Details ### Valid casts Cast context defines when casts may occur. Cast context | Definition | Strictness --------|------------|----------- **Implicit** | Values are automatically converted. For example, when you add `int4` to `int8`, the `int4` value is automatically converted to `int8`. | Least **Assignment** | Values of one type are converted automatically when inserted into a column of a different type. | Medium **Explicit** | You must invoke `CAST` deliberately. | Most Casts allowed in less strict contexts are also allowed in stricter contexts. That is, implicit casts also occur by assignment, and both implicit casts and casts by assignment can be explicitly invoked. Source type | Return type | Cast context -------------------------------------------|-----------------------------------------------|---------- [`array`](../../types/array/)1 | [`text`](../../types/text/) | Assignment [`bigint`](../../types/integer/) | [`bool`](../../types/boolean/) | Explicit [`bigint`](../../types/integer/) | [`int`](../../types/integer/) | Assignment [`bigint`](../../types/integer/) | [`float`](../../types/float/) | Implicit [`bigint`](../../types/integer/) | [`numeric`](../../types/numeric/) | Implicit [`bigint`](../../types/integer/) | [`real`](../../types/real/) | Implicit [`bigint`](../../types/integer/) | [`text`](../../types/text/) | Assignment [`bigint`](../../types/integer/) | [`uint2`](../../types/uint/) | Assignment [`bigint`](../../types/integer/) | [`uint4`](../../types/uint/) | Assignment [`bigint`](../../types/integer/) | [`uint8`](../../types/uint/) | Assignment [`bool`](../../types/boolean/) | [`int`](../../types/integer/) | Explicit [`bool`](../../types/boolean/) | [`text`](../../types/text/) | Assignment [`bytea`](../../types/bytea/) | [`text`](../../types/text/) | Assignment [`date`](../../types/date/) | [`text`](../../types/text/) | Assignment [`date`](../../types/date/) | [`timestamp`](../../types/timestamp/) | Implicit [`date`](../../types/date/) | [`timestamptz`](../../types/timestamp/) | Implicit [`float`](../../types/float/) | [`bigint`](../../types/integer/) | Assignment [`float`](../../types/float/) | [`int`](../../types/integer/) | Assignment [`float`](../../types/float/) | [`numeric`](../../types/numeric/)2 | Assignment [`float`](../../types/float/) | [`real`](../../types/real/) | Assignment [`float`](../../types/float/) | [`text`](../../types/text/) | Assignment [`float`](../../types/float/) | [`uint2`](../../types/uint/) | Assignment [`float`](../../types/float/) | [`uint4`](../../types/uint/) | Assignment [`float`](../../types/float/) | [`uint8`](../../types/uint/) | Assignment [`int`](../../types/integer/) | [`bigint`](../../types/integer/) | Implicit [`int`](../../types/integer/) | [`bool`](../../types/boolean/) | Explicit [`int`](../../types/integer/) | [`float`](../../types/float/) | Implicit [`int`](../../types/integer/) | [`numeric`](../../types/numeric/) | Implicit [`int`](../../types/integer/) | [`oid`](../../types/oid/) | Implicit [`int`](../../types/integer/) | [`real`](../../types/real/) | Implicit [`int`](../../types/integer/) | [`text`](../../types/text/) | Assignment [`int`](../../types/integer/) | [`uint2`](../../types/uint/) | Assignment [`int`](../../types/integer/) | [`uint4`](../../types/uint/) | Assignment [`int`](../../types/integer/) | [`uint8`](../../types/uint/) | Assignment [`interval`](../../types/interval/) | [`text`](../../types/text/) | Assignment [`interval`](../../types/interval/) | [`time`](../../types/time/) | Assignment [`jsonb`](../../types/jsonb/) | [`bigint`](../../types/integer/) | Explicit [`jsonb`](../../types/jsonb/) | [`float`](../../types/float/) | Explicit [`jsonb`](../../types/jsonb/) | [`int`](../../types/integer/) | Explicit [`jsonb`](../../types/jsonb/) | [`real`](../../types/real/) | Explicit [`jsonb`](../../types/jsonb/) | [`numeric`](../../types/numeric/) | Explicit [`jsonb`](../../types/jsonb/) | [`text`](../../types/text/) | Assignment [`list`](../../types/list/)1 | [`list`](../../types/list/) | Implicit [`list`](../../types/list/)1 | [`text`](../../types/text/) | Assignment [`map`](../../types/map/) | [`text`](../../types/text/) | Assignment [`mz_aclitem`](../../types/mz_aclitem/) | [`text`](../../types/text/) | Explicit [`numeric`](../../types/numeric/) | [`bigint`](../../types/integer/) | Assignment [`numeric`](../../types/numeric/) | [`float`](../../types/float/) | Implicit [`numeric`](../../types/numeric/) | [`int`](../../types/integer/) | Assignment [`numeric`](../../types/numeric/) | [`real`](../../types/real/) | Implicit [`numeric`](../../types/numeric/) | [`text`](../../types/text/) | Assignment [`numeric`](../../types/numeric/) | [`uint2`](../../types/uint/) | Assignment [`numeric`](../../types/numeric/) | [`uint4`](../../types/uint/) | Assignment [`numeric`](../../types/numeric/) | [`uint8`](../../types/uint/) | Assignment [`oid`](../../types/oid/) | [`int`](../../types/integer/) | Assignment [`oid`](../../types/oid/) | [`text`](../../types/text/) | Explicit [`real`](../../types/real/) | [`bigint`](../../types/integer/) | Assignment [`real`](../../types/real/) | [`float`](../../types/float/) | Implicit [`real`](../../types/real/) | [`int`](../../types/integer/) | Assignment [`real`](../../types/real/) | [`numeric`](../../types/numeric/) | Assignment [`real`](../../types/real/) | [`text`](../../types/text/) | Assignment [`real`](../../types/real/) | [`uint2`](../../types/uint/) | Assignment [`real`](../../types/real/) | [`uint4`](../../types/uint/) | Assignment [`real`](../../types/real/) | [`uint8`](../../types/uint/) | Assignment [`record`](../../types/record/) | [`text`](../../types/text/) | Assignment [`smallint`](../../types/integer/) | [`bigint`](../../types/integer/) | Implicit [`smallint`](../../types/integer/) | [`float`](../../types/float/) | Implicit [`smallint`](../../types/integer/) | [`int`](../../types/integer/) | Implicit [`smallint`](../../types/integer/) | [`numeric`](../../types/numeric/) | Implicit [`smallint`](../../types/integer/) | [`oid`](../../types/oid/) | Implicit [`smallint`](../../types/integer/) | [`real`](../../types/real/) | Implicit [`smallint`](../../types/integer/) | [`text`](../../types/text/) | Assignment [`smallint`](../../types/integer/) | [`uint2`](../../types/uint/) | Assignment [`smallint`](../../types/integer/) | [`uint4`](../../types/uint/) | Assignment [`smallint`](../../types/integer/) | [`uint8`](../../types/uint/) | Assignment [`text`](../../types/text/) | [`bigint`](../../types/integer/) | Explicit [`text`](../../types/text/) | [`bool`](../../types/boolean/) | Explicit [`text`](../../types/text/) | [`bytea`](../../types/bytea/) | Explicit [`text`](../../types/text/) | [`date`](../../types/date/) | Explicit [`text`](../../types/text/) | [`float`](../../types/float/) | Explicit [`text`](../../types/text/) | [`int`](../../types/integer/) | Explicit [`text`](../../types/text/) | [`interval`](../../types/interval/) | Explicit [`text`](../../types/text/) | [`jsonb`](../../types/jsonb/) | Explicit [`text`](../../types/text/) | [`list`](../../types/list/) | Explicit [`text`](../../types/text/) | [`map`](../../types/map/) | Explicit [`text`](../../types/text/) | [`numeric`](../../types/numeric/) | Explicit [`text`](../../types/text/) | [`oid`](../../types/oid/) | Explicit [`text`](../../types/text/) | [`real`](../../types/real/) | Explicit [`text`](../../types/text/) | [`time`](../../types/time/) | Explicit [`text`](../../types/text/) | [`timestamp`](../../types/timestamp/) | Explicit [`text`](../../types/text/) | [`timestamptz`](../../types/timestamp/) | Explicit [`text`](../../types/text/) | [`uint2`](../../types/uint/) | Explicit [`text`](../../types/text/) | [`uint4`](../../types/uint/) | Assignment [`text`](../../types/text/) | [`uint8`](../../types/uint/) | Assignment [`text`](../../types/text/) | [`uuid`](../../types/uuid/) | Explicit [`time`](../../types/time/) | [`interval`](../../types/interval/) | Implicit [`time`](../../types/time/) | [`text`](../../types/text/) | Assignment [`timestamp`](../../types/timestamp/) | [`date`](../../types/date/) | Assignment [`timestamp`](../../types/timestamp/) | [`text`](../../types/text/) | Assignment [`timestamp`](../../types/timestamp/) | [`timestamptz`](../../types/timestamp/) | Implicit [`timestamptz`](../../types/timestamp/) | [`date`](../../types/date/) | Assignment [`timestamptz`](../../types/timestamp/) | [`text`](../../types/text/) | Assignment [`timestamptz`](../../types/timestamp/) | [`timestamp`](../../types/timestamp/) | Assignment [`uint2`](../../types/uint/) | [`bigint`](../../types/integer/) | Implicit [`uint2`](../../types/uint/) | [`float`](../../types/float/) | Implicit [`uint2`](../../types/uint/) | [`int`](../../types/integer/) | Implicit [`uint2`](../../types/uint/) | [`numeric`](../../types/numeric/) | Implicit [`uint2`](../../types/uint/) | [`real`](../../types/real/) | Implicit [`uint2`](../../types/uint/) | [`text`](../../types/text/) | Assignment [`uint2`](../../types/uint/) | [`uint4`](../../types/uint/) | Implicit [`uint2`](../../types/uint/) | [`uint8`](../../types/uint/) | Implicit [`uint4`](../../types/uint) | [`bigint`](../../types/integer/) | Implicit [`uint4`](../../types/uint) | [`float`](../../types/float/) | Implicit [`uint4`](../../types/uint) | [`int`](../../types/integer/) | Assignment [`uint4`](../../types/uint) | [`numeric`](../../types/numeric/) | Implicit [`uint4`](../../types/uint) | [`real`](../../types/real/) | Implicit [`uint4`](../../types/uint) | [`text`](../../types/text/) | Assignment [`uint4`](../../types/uint) | [`uint2`](../../types/uint/) | Assignment [`uint4`](../../types/uint) | [`uint8`](../../types/uint/) | Implicit [`uint8`](../../types/uint/) | [`bigint`](../../types/integer/) | Assignment [`uint8`](../../types/uint/) | [`float`](../../types/float/) | Implicit [`uint8`](../../types/uint/) | [`int`](../../types/integer/) | Assignment [`uint8`](../../types/uint/) | [`real`](../../types/real/) | Implicit [`uint8`](../../types/uint/) | [`uint2`](../../types/uint/) | Assignment [`uint8`](../../types/uint/) | [`uint4`](../../types/uint/) | Assignment [`uuid`](../../types/uuid/) | [`text`](../../types/text/) | Assignment 1 [`Arrays`](../../types/array/) and [`lists`](../../types/list) are composite types subject to special constraints. See their respective type documentation for details. 2 Casting a [`float`](../../types/float/) to a [`numeric`](../../types/numeric/) can yield an imprecise result due to the floating point arithmetic involved in the conversion. ## Examples ```mzsql SELECT INT '4'; ``` ```nofmt ?column? ---------- 4 ```
```mzsql SELECT CAST (CAST (100.21 AS numeric(10, 2)) AS float) AS dec_to_float; ``` ```nofmt dec_to_float -------------- 100.21 ```
```mzsql SELECT 100.21::numeric(10, 2)::float AS dec_to_float; ``` ```nofmt dec_to_float -------------- 100.21 ``` ## Related topics * [Data Types](../../types/)