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#Mysql enum how to
#Mysql enum windows

Comparing to the look-up table ( priorities), an enumeration list is not reusable.

In this case, you need to have a separate table for storing priority list e.g., priorities(id, name, sort_order, description) and replace the priority field in the tickets table by priority_id that references to the id field of the priorities table. Suppose you want to add a service agreement for each priority e.g., High (24h), Medium (1-2 days), Low (1 week), it is not possible with ENUM.

Adding more attributes to the enumeration list is impossible.

Porting to other RDBMS could be an issue because ENUM is not SQL-standard and not many database system support it.

Getting the complete enumeration list is complex because you need to access the information_schema database: SELECT.

Changing enumeration members requires rebuilding the entire table using the ALTER TABLE statement, which is expensive in terms of resources and time.

MySQL ENUM has the following disadvantages: It’s always a good practice to define the enumeration values in the order that you want to sort when you create the column. The following query selects the tickets and sorts them by the priority from High to Low: SELECT Therefore, the order of member depends on how they were defined in the enumeration list. MySQL sorts ENUM values based on their index numbers. The following statement gets all high priority tickets: SELECTīecause the enumeration member ‘High’ is mapped to 3, the following query returns the same result set: SELECTĬode language: SQL (Structured Query Language) ( sql ) Sorting MySQL ENUM values Note that an ENUM column can accept NULL values if it is defined as a null-able column. In case the strict SQL mode is enabled, trying to insert an invalid ENUM value will result in an error.

In the non-strict SQL mode, if you insert an invalid value into an ENUM column, MySQL will use an empty string '' with the numeric index 0 for inserting. See the following statement: INSERT INTO tickets(title) ( 'Create a new user for the new employee David', 'High') īecause we defined the priority as a NOT NULL column, when you insert a new row without specifying the value for the priority column, MySQL will use the first enumeration member as the default value.

Let’s add some more rows to the tickets table: INSERT INTO tickets(title, priority) Since Low is mapped to 1, it is acceptable. In this example, instead of using the Low enumeration value, we used value 1.

#Mysql enum windows

VALUES( 'Upgrade Windows OS for all computers', 1) For instance, the following statement inserts a new ticket with the Low priority: INSERT INTO tickets(title, priority) VALUES( 'Scan virus for computer A', 'High') īesides the enumeration values, you can use the numeric index of the enumeration member for inserting data into an ENUM column. For example, the following statement inserts a new row into the tickets table. To insert data into an ENUM column, you use the enumeration values in the predefined list. In this case, Low, Medium, and High are map to 1, 2 and 3 respectively.

Behind the scenes, MySQL maps each enumeration member to a numeric index. The priority column will accept only three values Low, Medium and High. Priority ENUM( 'Low', 'Medium', 'High') NOT NULL To assign the priority column the ENUM type, you use the following CREATE TABLE statement: CREATE TABLE tickets ( Suppose, we have to store ticket information with the priority: low, medium, and high. However, it is a good practice to keep the number of enumeration values under 20. In this syntax, you can have more than three enumeration values. To define an ENUM column, you use the following syntax: CREATE TABLE table_name (Ĭol ENUM ( 'value1', 'value2', 'value3'),Ĭode language: SQL (Structured Query Language) ( sql ) MySQL ENUM uses numeric indexes (1, 2, 3, …) to represents string values. The ENUM data type provides the following advantages: In MySQL, an ENUM is a string object whose value is chosen from a list of permitted values defined at the time of column creation.

#Mysql enum how to

Summary: in this tutorial, you will learn how to use MySQL ENUM data type for defining columns that store enumeration values.