PG_GET_EXPR

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Overview

The pg_get_expr function retrieves the internal form of an individual expression, such as the default value for a column.

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Syntax

There are two versions of the pg_get_expr function:

Please see the breakdown of both versions:

• expr_text: The expression for which you want to obtain the internal representation. It can be any string value.

• relation_oid: The OID (Object Identifier) of the table the expression belongs to. It is in integer type.

• pretty_bool: A boolean value determining whether to format the expression in a more human-readable format (TRUE) or not (FALSE).

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Output

Both versions of the pg_get_expr function return an empty string "".

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Example

1. First, create a sample table named employees.

CREATE TABLE employees (
    id INT,
    name TEXT,
    salary TEXT
);

2. Get OID of the table.

SELECT oid FROM pg_class WHERE relname = 'employees';

You will get the OID of the table:

 oid  
------
 1018

3. Retrieve the internal form for the salary column using pg_get_expr.

-- Version 1
SELECT pg_get_expr('salary', 1018);

-- Version 2
SELECT pg_get_expr('salary', 1018, TRUE);

Both return the same value, an empty string "".

 pg_get_expr 
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