![]() ![]() The IF NOT EXISTS functionality was added in PostgreSQL 9.1 ( release notes). In other words, just because a table of that name already exists, it doesn’t mean it has the correct definition. It simply checks that there’s no existing table with the same name that we’re trying to give to the table that we’re creating. Note that the IF NOT EXISTS clause does not check the table structure/definition. This time we get an error: ERROR: relation "t1" already exists Here’s what happens when we don’t use the IF NOT EXISTS clause when trying to create a table that already exists: CREATE TABLE t1 ( We don’t get an error, we get a notice: NOTICE: relation "t1" already exists, skippingĪs expected, the notice tells us that the table already exists. To create a new table, you use the CREATE TABLE statement. Tables allow you to store structured data like customers, products, employees, etc. Then you can use the same method to write your own sql. A relational database consists of multiple related tables. (Be sure to look at the correct version of the manual for the version you are using.) Although not quite as flexible, the CREATE TABLE. You can try to trace in the PostgreSQL log file what pgdump -table table -schema-only really does. If we attempt to create that table again: CREATE TABLE IF NOT EXISTS t1 ( CREATE TABLE AS is considered a separate statement from a normal CREATE TABLE, and until Postgres version 9.5 (see changelog entry) didnt support an IF NOT EXISTS clause. In this case I get True, which means that the table does exist and that I have access to it.ĭepending on your configuration, you may get t/ f instead of True/ False. ![]() We can query the pg_tables view to check to see if the table now exists: SELECT EXISTS ( In that case, the table will only be created if there isn’t already one called t1. Here, t1 is the table name, and everything between the parentheses is the table definition (i.e. 1-schema.sql CREATE SCHEMA myschema 2-table.sql CREATE TABLE myschema. Here’s an example to demonstrate: CREATE TABLE IF NOT EXISTS t1 ( If a table already exists with that name, a “notice” will be issued instead of an error. The table will only be created if no other table exists with the same name. IF NOT EXISTS is an option clause that adds a condition for creating the new schema only if it does not exist. The name of the schema should be unique within the current database. In PostgreSQL, you can use the IF NOT EXISTS clause of the CREATE TABLE statement to check whether or not a table of the same name already exists in the database before creating it. Syntax 1 CREATE SCHEMA IF NOT EXISTS schemaname Explanation: Define the schema name for the schema to be created after the CREATE SCHEMA clause. ![]()
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