In SQLite, you can use the IF NOT EXISTS clause of the CREATE TABLE statement to check whether or not a table or view of the same name already exists in the database before creating it.
Creating a table without this clause would normally result in an error if a table of the same name already existed in the database. But when using the IF NOT EXISTS clause, the statement has no effect if a table already exists with the same name.
T-SQL doesn’t include the IF NOT EXISTS clause with its CREATE TABLE statement, like some other DBMSs do.
Therefore, if we want to check for the existence of the table before we create it in SQL Server, we need to use other methods.
Continue readingIn PostgreSQL, we can use the IF EXISTS clause of the DROP TABLE statement to check whether the table exists or not before dropping it.
In Oracle Database, there are a number of views that we can query to find out whether a table exists.
Continue readingSome DBMSs such as Oracle, MySQL, and MariaDB have a DESCRIBE command that returns information about tables and views. It goes DESCRIBE table where table is the name of the table or view, and it can also be followed by a column name if you only want information about a specific column.
PostgreSQL doesn’t have a DESCRIBE TABLE command as such, but there are alternatives.
In SQLite, we can use the IF EXISTS clause of the DROP TABLE statement to check whether the table exists or not before dropping it.
In SQLite, the table_list pragma returns information about the tables and views in the schema.
It was first introduced in SQLite version 3.37.0 (released on 2021-11-27).
Continue readingIn MariaDB, we can use the IF EXISTS clause of the DROP TABLE statement to check whether the table exists or not before dropping it.
The very useful DROP TABLE IF EXISTS syntax was finally introduced in Oracle Database – Oracle Database 23c to be precise. This syntax allows us to run a DROP TABLE statement without getting an error if the table doesn’t exist.
Earlier versions of Oracle don’t support the IF EXISTS clause. Therefore, if we want to avoid any nasty errors resulting from trying to drop a non-existent table, we need to do a bit of extra work.
Below are three options for dropping a table if it exists in Oracle.
Continue readingIn MySQL, we can use the IF EXISTS clause of the DROP TABLE statement to check whether the table exists or not before dropping it.