![]() We then only run the CREATE TABLE statement if it doesn’t already exist. Here, we checked the DBA_TABLES data dictionary view to see if the table already exists. One option is to check the DBA_TABLES data dictionary view: DECLARE Oracle Database doesn’t support the CREATE TABLE IF NOT EXISTS statement either, so we also need to use a different method with Oracle. This is one of at least two methods for creating a table only if it doesn’t exist in SQL Server. ![]() Therefore, we can check for a NULL value, and only create the table if this function returns NULL. If the object doesn’t exist, or if we don’t have access to it, the function returns NULL. The OBJECT_ID() returns the database object identification number of a schema-scoped object. In this case we use U, which is for “user defined table”. The second argument specifies the type of object we’re looking for. In this example we’re checking the object ID of a dbo.t1 table. One option is to use the OBJECT_ID() function to check for the existence of the table before we try to create it: IF OBJECT_ID(N'dbo.t1', N'U') IS NULL SQL Server doesn’t support the CREATE TABLE IF NOT EXISTS statement, so we need to use another option. The CREATE TABLE IF NOT EXISTS statement isn’t supported by SQL Server or Oracle (at least not at the time of writing), but we can use one of the methods below. The CREATE TABLE IF NOT EXISTS statement can be used with RDBMSs such as MySQL, MariaDB, PostgreSQL, and SQLite. In this 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. Many RDBMSs support the IF NOT EXISTS clause of the CREATE TABLE statement which makes it easy to create a table only when it doesn’t already exist. Here are some examples of doing this in various RDBMSs. Doing this prevents any errors from occurring in the event that the table already exists. When creating a table with SQL, we can specify that the table is only to be created if it doesn’t already exist.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |