How Can I Store PostgreSQL Query Results in a PL/pgSQL Variable?
Use PL/pgSQL to store query results into variables
PostgreSQL’s procedural language PL/pgSQL allows assigning the results of SQL queries to variables. This enables efficient processing and manipulation of data in stored procedures and functions.
SELECT INTO syntax
To store query results into variables, PL/pgSQL uses the SELECT INTO
syntax. The syntax has the form:
SELECT select_expressions INTO target_variable FROM table_or_query_expression;
Example:
The following PL/pgSQL function attempts to retrieve a name from a table based on an input ID:
-- PL/pgSQL 函数 CREATE OR REPLACE FUNCTION test(x numeric) RETURNS character varying AS $BODY$ DECLARE name character varying(255); BEGIN -- 正确的方法 SELECT name INTO name FROM test_table WHERE id = x; RETURN name; EXCEPTION WHEN NO_DATA_FOUND THEN RETURN NULL; END; $BODY$ LANGUAGE plpgsql;
In this example, we use SELECT INTO
to assign the value of the test_table
field in the name
table to the variable name
. This ensures that the variable contains the desired result.
SELECT
clause specifies the test_table
columns selected from the name
table. INTO
The keyword is followed by the variable (name) in which the result will be stored. The EXCEPTION
block is added to the error handling section to handle the NO_DATA_FOUND
situation and return NULL
.
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