sql - Pass column name to a function - 


create or replace function test123(column_name varchar(40)) returns record $$ declare        rec record ; begin     select * rec my_table column_name=1 limit 1;     return rec; end; $$ language plpgsql;

how can pass column name function , use name in query?

the above code not work:

error: operator not exist: character varying = integer

when want use function parameters identifiers in queries inside function need dynamically execute query:

create or replace function test123(column_name varchar(40)) returns record $$ declare        rec record; begin     execute format('select * my_table %i = 1 limit 1', column_name)     rec;     return rec; end; $$ language plpgsql;

or shorter:

create or replace function test123(column_name varchar(40)) returns record $$ begin     return query execute format('select * my_table %i = 1 limit 1', column_name); end; $$ language plpgsql;

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