![]() ![]() Parameters ParameterĪdd a column only if a column of the same name does not already exist if one does exist, do not return an error. The user must have the CREATE privilege on the table. ADD COLUMN to add columns to existing tables.įor examples, see Add columns. Remove a range split enforcement in the table.Ĭheck whether values in a column match a constraint on the column. ![]() Set the table locality for a table in a multi-region database.įorce a range split at the specified row in the table. Reset a storage parameter on a table to its default value. Partition, re-partition, or un-partition a table. For example, you can atomically rename a column and add a new column with the old name of the existing column.Įnable per-table audit logs, for security purposes. Some subcommands can be used in combination in a single ALTER TABLE statement. The name of the table you want to change.Īdditional parameters are documented for the respective subcommands. Later on, you might consider to drop unused columns by ALTER TABLE.ADD COLUMN IF NOT EXISTS column_name typename col_qualification CONSTRAINT IF NOT EXISTS constraint_name constraint_elem NOT VALID RENAME COLUMN column_name TO column_new_name CONSTRAINT constraint_name TO constraint_new_name ALTER COLUMN column_name SET DEFAULT a_expr ON UPDATE b_expr VISIBLE NOT VISIBLE NULL DROP DEFAULT ON UPDATE NOT NULL STORED SET DATA TYPE typename COLLATE collation_name USING a_expr PRIMARY KEY USING COLUMNS ( index_params ) USING HASH WITH ( storage_parameter_key = value, ) DROP COLUMN IF EXISTS column_name CONSTRAINT IF EXISTS constraint_name CASCADE RESTRICT VALIDATE CONSTRAINT constraint_name EXPERIMENTAL_AUDIT SET READ WRITE OFF PARTITION ALL BY LIST ( name_list ) ( list_partitions RANGE ( name_list ) ( range_partitions ) NOTHING SET ( storage_parameter_key = value, RESET ( storage_parameter_key, ), Parameters ParameterĬhange the table only if a table with the current name exists if one does not exist, do not return an error. To add an unique index on a column, you should use ALTER TABLE ADD constraint statement. alter table t1 add (c8 number check (c8 < 10)) Īlter table t1 add (c8 number check (c8 < 10) not null) Īlter table t1 add (c8 number default 5 check (c8 < 10)) Īlter table t1 add (c8 number default 5 check (c8 < 10) not null) We add a check constraint to the column to limit the value within a scope. alter table t1 add (c6 varchar2(20) not null, c7 varchar2(20) not null) Check Value You can add two or more columns at a time in a single statement. alter table t1 add (c5 varchar2(20) default 'Banana' not null) Multiple Columns We combine both features to confine the column, which is a good practice to prevent ORA-01400: cannot insert NULL by providing a default value for NOT NULL column. alter table t1 add (c4 varchar2(20) not null) Default Value + NOT NULL NOT NULL is a kind of constraint to columns, it does not allow a NULL value to be inserted or updated. ![]() alter table t1 add (c3 varchar2(20) default 'Apple') NOT NULL To prevent fields from empty by accident, we can provide a default value for the column. alter table t1 add (c2 varchar2(20)) Default Value The basic form contains an identifier and its data type for the column. SQL> create table t1 (c1 number) Īs you can see, there should be at least one column in CREATE TABLE statement. Examples may vary in details, but the base clause ALTER TABLE ADD column is always the same.įirst of all, we create a table for testing. In this post, I'll show you some practical examples of adding a column to table from the simplest to the complicated. ![]()
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