type_conversion.md

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Type Conversion Functions and Operators

Function: CAST (Alias: CONVERT)

Description:
Converts a value to a specified SQL type. Fails if the conversion is invalid.

Inputs:

• value (ANY type)
• targetType (SQL type: INT, BIGINT, DOUBLE, DATE, DATETIME, TIMESTAMP, VARCHAR, etc.)

Output:

• targetType

Example:

SELECT CAST('2025-09-11' AS DATE) AS d;
-- Result: 2025-09-11

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Function: TRY_CAST (Alias: SAFE_CAST)

Description:
Attempts to convert a value to a specified SQL type. Returns NULL if the conversion fails instead of raising an error.

Inputs:

• value (ANY type)
• targetType (SQL type: INT, BIGINT, DOUBLE, DATE, DATETIME, etc.)

Output:

• targetType (nullable)

Example:

SELECT TRY_CAST('invalid-date' AS DATE) AS d;
-- Result: NULL

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Operator: :: (Cast Operator)

Description:
Shorthand operator for casting. Equivalent to CAST(value AS type).

Inputs:

• value (ANY type)
• targetType (SQLType)

Output:

• targetType

Example:

SELECT '2025-09-11'::DATE AS d, '125'::BIGINT AS b;
-- Result: 2025-09-11, 125

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Behavior Notes

• CAST (CONVERT) will raise errors on invalid conversions.
• TRY_CAST (SAFE_CAST) returns NULL instead of failing.
• :: is syntactic sugar, easier to read in queries.
• Type inference relies on baseType, and explicit CAST/TRY_CAST/:: updates the type context for following functions.

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