Notice: If you actually don't want to return a query result but execute a DML (or a DDL should work too) you could also put it in an anonymous block without defining a function. If specified, the table will only be dropped if there are no other objects that depend on it.
Otherwise the SELECT in the function fails. If specified, the DROP TABLE statement will not raise an error if one of the tables does not exist. You'd have to RAISE an error then (But if you want that you could have just used a normal SELECT that croaks anyway, if the target table doesn't exist.)Īnd the table has to have the expected columns. CREATE TABLE elbatīut you cannot distinguish from outside, just by calling the function, if you got an empty set because the table doesn't exist or because it is empty. The following SQL statement drops the existing table. You can disable the display of those notices trough the property clientminmessages which controls the minimum level of messages returned to the client. Deleting a table will result in loss of complete information stored in the table SQL DROP TABLE Example. When the table does not exist you get the empty set.Ĭreate the table, call it again and you'll get the contents of the table. 1 Answer Sorted by: 9 The 'warning' is in fact a 'notice'. import psycopg2 Connect to the PostgreSQL database conn nnect ( host'yourhost', database'yourdatabase', user'yourusername', password'yourpassword' ) Create a cursor object to execute SQL commands cur conn.cursor () Define the name of the table to delete tablename 'yourtablename' Define the SQL query to.
#Postgresql delete table if exists how to
How to delete values from table passed on a condition on another table. Before dropping a table, you must first remove any.
Deleting partial rows conditionally in postgresql. If the table does not exist and you do not include the IF EXISTS clause, the statement will return an error. For example, it is possible to add several columns and/or alter the type of several columns in a single command. How can I delete rows if some condition in postgres. All the forms of ALTER TABLE that act on a single table, except RENAME, SET SCHEMA, ATTACH PARTITION, and DETACH PARTITION can be combined into a list of multiple alterations to be applied together. PostgreSQL - Delete rows in table based on values in other table.
#Postgresql delete table if exists update
You could (and likely have to) wrap that in a function. Update where exists delete row where doesnt. You should probably use a stored procedure to to do this: DELIMITER DROP PROCEDURE IF EXISTS test.DeleteByID CREATE PROCEDURE test.DeleteByID (db VARCHAR(64),tb VARCHAR(64),idtodelete INT) BEGIN DECLARE FoundCount INT SELECT COUNT(1) INTO FoundCount FROM informationschema.tables WHERE tableschema db AND tablename tb IF FoundCount 1 THEN SET sql CONCAT('DELETE FROM.
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