) Code language: SQL (Structured Query Language) ( sql ) How MySQL sequence works The following statement creates a table named employees that has the emp_no column is an AUTO_INCREMENT column: When you set the AUTO_INCREMENT attribute to a column, MySQL automatically adds the NOT NULL constraint to the column implicitly. The AUTO_INCREMENT column must have a NOT NULL constraint.The AUTO_INCREMENT column must be indexed, which means it can be either PRIMARY KEY or UNIQUE index.Each table has only one AUTO_INCREMENT column whose data type is typically the integer.The following rules are applied when you use the AUTO_INCREMENT attribute: To create a sequence in MySQL automatically, you set the AUTO_INCREMENT attribute for a column, which typically is a primary key column. In MySQL, a sequence is a list of integers generated in the ascending order i.e., 1,2,3… Many applications need sequences to generate unique numbers mainly for identification e.g., customer ID in CRM, employee numbers in HR, and equipment numbers in the services management system.
Summary: in this tutorial, you will learn how to use MySQL sequence to automatically generate unique numbers for ID columns of tables.
0 kommentar(er)
