Search results
SQL PRIMARY KEY on ALTER TABLE. To create a PRIMARY KEY constraint on the "ID" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access:
This tutorial shows you how to use Oracle PRIMARY KEY constraint to create, add, disable, enable, and drop a primary key of a table.
20 paź 2008 · A Table can have a Composite Primary Key which is a primary key made from two or more columns. For example: CREATE TABLE userdata ( userid INT, userdataid INT, info char(200), primary key (userid, userdataid) ); Update: Here is a link with a more detailed description of composite primary keys.
You can create a primary key in Oracle with the ALTER TABLE statement. Syntax. The syntax to create a primary key using the ALTER TABLE statement in Oracle/PLSQL is: ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column1, column2, ... column_n); Example. Let's look at an example of how to create a primary key using the ALTER ...
28 sie 2015 · If we want to make our table to have primary key set {old_key, new_key}, then the following statement can be used: ALTER TABLE my_test_table DROP PRIMARY KEY, -- You have to add this ADD PRIMARY KEY( old_key, -- Re-mention the old key new_key -- And mention also the new one );
To create a new table with a column defined as the primary key, you can use the keyword PRIMARY KEY at the end of the definition of that column. In our example, we create the table product using a CREATE TABLE clause, with the names of the columns and their respective data types in parentheses.
9 cze 2023 · Create Table Primary Key Syntax. You can specify a primary key on a table when you create in two ways: Next to the column data type when you declare it on the same line (an inline constraint) At the end of all column declarations (an out of line constraint)
