conditional IF statements in postgresql - Mailing list pgsql-general

From Madhurima Das
Subject conditional IF statements in postgresql
Date
Msg-id CAMsahj3X2euJb-fjAtD7EfgbJXRgAwZj8rqiJDEdbW0Yoi2_Qg@mail.gmail.com
Whole thread Raw
Responses Re: conditional IF statements in postgresql  (David G Johnston <david.g.johnston@gmail.com>)
Re: conditional IF statements in postgresql  (Albe Laurenz <laurenz.albe@wien.gv.at>)
List pgsql-general
Hi,

I am writing a C program to access a PostgreSQL database, where 

I add a column if it doesn't exists in the table

or, update the column, if the column already exits.

Please suggest how to work with the conditional statements.

Thanks!

N.B. I wrote the following:

res = PQexec(conn, "IF COL_LENGTH('protein_sequence','comment') IS NULL");
PQclear(res);
if(res)
 {
     res = PQexec(conn, "ALTER TABLE protein_sequence ADD comment VARCHAR(500)");
     PQclear(res);
 }
 else
 {
     res = PQexec(conn, "UPDATE TABLE protein_sequence ADD comment VARCHAR(500)");
      PQclear(res);
 }

Is the code logically correct??

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