It is pretty simple and can be used effectively to implement an IF EXISTS in a CASE notation. If the table already exists, it would return a Success else, it would call the table creation function. It returns a true when tablename is equal to table_one. The SELECT CASE is the same as an if else statement. It replaces the simple SELECT query with a CASE statement. The above code is no different than the method given above. WHERE tablename = 'table_one' ) THEN ( SELECT 'success' :: void)ĮLSE ( SELECT create_user_specific_table()) SELECT CASE WHEN ( SELECT true :: BOOLEAN FROM pg_catalog. Use a CASE Statement to Create a Table if It Does Not Exist in PostgreSQLĬREATE OR REPLACE FUNCTION create_user_specific_table()ĬREATE TABLE table_one (u_name varchar(50) not null You can also modify this function as it fits better to your needs. The RAISE NOTICE function is what implements this functionality.ĭifferent implementations of this function can be used to CREATE a table in PostgreSQL. A column must be declared with its data type, and each columns should be separated by a comma. The students table has five columns to store the students’ ID, name, GPA, enrollment date, and status of completion of the degree. Instead, it will raise a notice that The table already exists. The CREATE TABLE statement lets you create a table in the database. Inside the function, if the table is already present inside the listed tables, it won’t be created. The $func$ is the start and end tag of the function. In PostgreSQL, the CREATE TABLE clause as the name suggests is used to create new tables. It can be used effectively for testing, rather than deleting the function listed and then creating it again. The following SQL statement will create a table named cars in your PostgreSQL. Hence, you won’t run into an error while calling the function again and again. Once you are connected, you are ready to write SQL statements Create Table. You’ll see the CREATE or REPLACE written behind the function defined.ĬREATE or REPLACE tends to replace the existing function definition given inside the system if it has already been integrated inside the database. Now, let’s try to analyze how this works. INSERT INTO table_one (u_name) values( 'Jonathon') Then, create a cursor object by calling the cursor () method of the connection object. The connect () function returns a connection object. Next, connect to the PostgreSQL database by calling the connect () function. RAISE NOTICE 'Table table_one already exists.' ĬREATE TABLE table_one (u_name varchar(50)) To create a new table in a PostgreSQL database, you use the following steps: First, construct CREATE TABLE statements. IF EXISTS (SELECT FROM pg_catalog.pg_tables CREATE or replace FUNCTION create_user_specific_table()
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