How Can I Cast Data Types in PostgreSQL?

Detailed explanation of PostgreSQL data type conversion

Easily convert a column's data type to other types in a SELECT statement in PostgreSQL. Here’s how:

<code class="language-sql">SELECT cast(varchar_col AS int) FROM table_name;</code>

This syntax complies with SQL standards. Alternatively, PostgreSQL allows the shorthand syntax:

<code class="language-sql">SELECT varchar_col::int FROM table_name;</code>

Both variations can be used almost anywhere, but the second form may require parentheses when nesting.

Additionally, you can use the following syntax variations:

<code class="language-sql">int4(varchar_col)
int '123'</code>

Note that int4() uses an internal type name, whereas int '123' expects an untyped quoted string literal. However, int[] '{1,2,3}' must be converted using '{1,2,3}'::int[] or cast('{1,2,3}' AS int[]) .

For more information, please refer to the section on conversion functions and array types in the PostgreSQL documentation.

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