MariaDB Alter Table If Exists

The MariaDB Alter Table If Exists statement will be covered in detail, along with several examples, in this MariaDB tutorial. There are listings of the subject matter that is discussed:

• MariaDB Alter Table If Exists
• MariaDB Alter Table Drop Index If Exists
• MariaDB Alter Table Add Index If Not Exists
• MariaDB Alter Table Add Constraint If Not Exists
• MariaDB Alter Table Add Column If Not Exists
• MariaDB Alter Table Drop Column If Exists

MariaDB Alter Table If Exists

In this MariaDB subtopic tutorial, we will learn and understand how to use the MariaDB ALTER TABLE statement with the IF EXISTS clause on the table by the query, which will be explained with the help of an illustrated example.

In MariaDB, the ALTER TABLE statement is used to add, modify, or drop/ delete column from the table. It is also used to rename columns of the table. The MariaDB IF EXISTS statement is used to check whether a column exists in the table or not.

Here is the syntax of the MariaDB ALTER TABLE IF EXISTS statement on the table by the following query:

SYNTAX:

ALTER TABLE TABLE_NAME ADD COLUMN [IF EXISTS] NEW_COLUMN_NAME COLUMN_DATATYPE
[FIRST | AFTER YOUR_COLUMN_NAME];

In the syntax explanation:

• TABLE_NAME: It is the name of the table to modify.
• NEW_COLUMN_NAME: It is the name of the column which is added to the table.
• COLUMN_DATATYPE: The datatype and definition of the column i.e; (NULL or NOT NULL).
• FIRST | AFTER COLUMN_NAME: It tells MariaDB were in the table to create a column. If this parameter is not used then the new column will be added to the end of the table.

Here is a sample example of the MariaDB ALTER TABLE IF EXISTS statement on the table by the following query:

EXAMPLE:

ALTER TABLE UNITED_STATEOF_AMERICA ADD COLUMN IF EXISTS LASTDATE_STATE DATETIME NOT NULL 
AFTER STATE_ENTERDATE;

In the aforementioned query, we have used the ALTER TABLE statement with the IF EXISTS clause to add a column called LASTDATE_STATE column with the DATETIME datatype in the UNITED_STATEOF_AMERICA table. It is also added the NOT NULL value in the new column and the new column will be available after the STATE_ENTERDATE column in the UNITED_STATEOF_AMERICA table.

We hope that you have understood how to use the MariaDB ALTER TABLE IF EXIST statement on the table by the query. For a better explanation, we have used an example and explained it in depth.

Read: MariaDB Select Unique

MariaDB Alter Table Drop Index If Exists

Here we will learn and understand how to use the MariaDB ALTER TABLE statement used with the IF EXISTS clause to drop an index_name by the query, which will be explained with the help of syntax and an example.

SYNTAX:

ALTER TABLE DROP INDEX IF EXISTS YOUR_INDEX_NAME;

In the syntax explanation:

• First, we need to specify the name of the index that we want to delete after using the DROP INDEX clause. As an optional, the IF EXISTS clause conditionally terminates the index if it exists.

EXAMPLE:

ALTER TABLE DROP INDEX IF EXISTS USA_STATES;

In the first query, we have used the ALTER TABLE statement to drop an index called USA_STATES by using the IF EXISTS clause. The IF EXISTS clause is a condition that will be used to check whether an index is created or not on the particular table.

We hope that you have understood the subtopic “MariaDB Alter Table Drop Index If Exists” by using the MariaDB ALTER TABLE statement with the IF EXISTS clause on the table by the query. We have used an example and explained it in depth, for better understanding.

Read: MariaDB Date Allow Null

MariaDB Alter Table Add Index If Not Exists

Here we will learn and understand how to use the MariaDB ALTER TABLE statement with the IF NOT EXISTS clause to add an index to the table by the query, which is explained with the help of an example.

EXAMPLE:

CREATE TABLE UNITED_STATEOF_AMERICA(
STATE_ID INT AUTO_INCREMENT PRIMARY KEY, 
STATE_NAME VARCHAR(50)); 

ALTER TABLE ADD INDEX IF NOT EXISTS STATEID;

In the first query, we have created a table called the UNITED_STATEOF_AMERICA table by using the CREATE TABLE statement. Then we created an index called STATEID on the STATE_ID column in the UNITED_STATEOF_AMERICA table by using the ALTER TABLE statement.

We hope that you have understood the subtopic “MariaDB Alter Table Add Index If Not Exists” by using the MariaDB ALTER TABLE statement on the table by the query. For a better explanation, we have used an example and explained it in depth.

Read: MariaDB Select Where Not Empty

MariaDB Alter Table Add Constraint If Not Exists

In this MariaDB section, we will learn and understand how to use the MariaDB ALTER TABLE statement to add constraint if not exists on the table by the following query:

EXAMPLE:

ALTER TABLE UNITED_STATEOF_AMERICA ADD CONSTRAINT IF NOT EXISTS 
STATE_NAME UNIQUE KEY;

DESC UNITED_STATEOF_AMERICA;

In the preceding query, we have used the ALTER TABLE statement to add constraint as UNIQUE KEY on the STATE_NAME column of the UNITED_STATEOF_AMERICA table. In the IF NOT EXISTS clause, it will check whether any type of key is added to that column or not. But if it is there then the query will show a syntax error.

We hope that you have understood the subtopic “MariaDB Alter Table Add Constraint If Not Exists” by using the MariaDB ALTER TABLE statement on the table by the query. For a better explanation, we have used an example and explained it in depth.

Read: MariaDB Check Empty String

MariaDB Alter Table Add Column If Not Exists

In this MariaDB tutorial, we will learn and understand how to use the MariaDB ALTER TABLE statement used with the IF NOT EXISTS clause on the table by the following query:

EXAMPLE:

ALTER TABLE UNITED_STATEOF_AMERICA ADD COLUMN IF NOT EXISTS STATE_EXISTDATE DATETIME;

DESC UNITED_STATEOF_AMERICA;

As we see in the above query, we have used the ALTER TABLE statement to add a new column called STATE_EXISTDATE with datatype DATETIME in the UNITED_STATEOF_AMERICA table.

In the IF NOT EXISTS clause, it will check whether a new column exists in the UNITED_STATEOF_AMERICA table or not but if it exists then it will throw an error. Otherwise, a new column will be added to the UNITED_STATEOF_AMERICA table.

If we want to see the changes in the UNITED_STATEOF_AMERICA table then we will use the DESC statement by the query.

We hope that you have understood the subtopic “MariaDB Alter Table Add Column If Not Exists” by using the MariaDB ALTER TABLE statement with the IF NOT EXISTS clause on the table by the query. For a better explanation, we have used an example and explained it in depth.

Read: MariaDB Check String Length

MariaDB Alter Table Drop Column If Exists

Here we will learn and understand how to use the MariaDB ALTER TABLE statement to drop column of the table with the IF EXISTS clause by the query. And which will be explained with the help of a syntax and a sample example.

SYNTAX:

ALTER TABLE YOUR_TABLE_NAME DROP COLUMN IF EXIST COLUMN_NAME;

In this syntax explanation:

• YOUR_TABLE_NAME: It is the name of the table which will be modified.
• COLUMN_NAME: It is the name of the column which will be deleted from the table.

EXAMPLE:

ALTER TABLE UNITED_STATEOF_AMERICA DROP COLUMN IF EXISTS FULL_NAME;

In the above query, we have used the ALTER TABLE statement to drop a column called FULL_NAME column from the UNITED_STATEOF_AMERICA table by using the IF EXISTS clause. In the IF EXISTS clause, it will check the FULL_NAME column exists then it will delete that column from the UNITED_STATEOF_AMERICA table.

But if the FULL_NAME column doesn’t exist in the UNITED_STATEOF_AMERICA table then the ALTER TABLE IF EXISTS statement will be executed but it will not delete the column_name from the UNITED_STATEOF_AMERICA table.

We hope that you have understood the subtopic “MariaDB Alter Table Drop Column If Exists” by using the MariaDB ALTER TABLE statement with the IF EXISTS clause on the table by the query. For a better explanation, we have used an example and demonstrated it in depth.

You may also like to read the following MariaDB tutorials.

• MariaDB Greatest Function
• MariaDB Insert Into Select
• MariaDB Not Between
• MariaDB Not Equal Operator
• MariaDB Show Column Data Type
• MariaDB Order By Multiple Columns
• MariaDB Create Database And User

In this MariaDB lesson, we covered the use of the MariaDB Alter Table If Exists statement and various sample instances related to it. There are several listings of the topics that are discussed:

• MariaDB Alter Table If Exists
• MariaDB Alter Table Drop Index If Exists
• MariaDB Alter Table Add Index If Not Exists
• MariaDB Alter Table Add Constraint If Not Exists
• MariaDB Alter Table Add Column If Not Exists
• MariaDB Alter Table Drop Column If Exists