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Synopsis

CAST ( expression AS target_type );

Or the operator:

expression :: target_type ;

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Description

The CAST function or operator are used to explicitly convert a value from one data type into a another data type.

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Casting Notes

  1. Casting BOOLEAN:
    • Casting strings: Only valid strings - ‘true’, ’false’, ’t’, ’f’ (case insensitive) - can be casted.
    • Casting numbers: Only integral_types can be converted. Note that all integers except 0 are converted to ‘true’. Zero is converted to ‘false’.
  2. When casting different string length without specifying the needed length, the result value is VARCHAR(max).

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Parameters

expression

The expression can be a constant or a column or any expression that resolves to a single value.

target_type

The target_type is the data type to which you want to convert the above expression to, as long as it is qualified as a valid convert.

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Examples

Convert literal representing a DATE into TIMESTAMP:

SELECT CAST('2022-12-12' AS TIMESTAMP);

Returns: 2022-12-12 00:00:00. Note that the time was added.

Convert literal representing an INT into STRING:

SELECT 234567::STRING;

Returns: ‘234567’

Convert literal representing numeric_type into DECIMAL:

SELECT CAST(10.4572 AS DECIMAL);

Returns: 10.4572

Convert the column value o_date into TIMESTAMP:

SELECT CAST(o_date AS TIMESTAMP) FROM orders;