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MySQL Articles
Page 313 of 355
Selecting a column that is also a keyword in MySQL?
To select a column that is also a keyword in MySQL, you need to use backticks around the column name. As you know select is a keyword in MySQL, consider column name as select when creating a new table.Let us create a table:mysql> create table DemoTable (`select` varchar(100)); Query OK, 0 rows affected (0.53 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable values('Records'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('All Data'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Information'); Query OK, 1 ...
Read MoreHow to check if data is NULL in MySQL?
You can use IF() to check if data is NULL. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(200), Age int ); Query OK, 0 rows affected (0.44 sec)Insert records in the table using insert command −mysql> insert into DemoTable(Name, Age) values('John', 23); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(Name, Age) values('Sam', null); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(Name, Age) values('Mike', 23); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(Name, Age) values('David', 21); Query OK, ...
Read MoreHow to display message from a stored procedure?
To display message from stored procedure on the basis of conditions, let us use IF-ELSE condition −mysql> DELIMITER // mysql> CREATE PROCEDURE showMessage(value int, Name varchar(20)) BEGIN IF(value > 100) then SELECT CONCAT("HELLO", " ", Name); ELSE SELECT CONCAT("BYE", " ", Name); END IF; END // Query OK, 0 rows affected (0.18 sec) mysql> DELIMITER ;Case 1 − Call the stored procedure using CALL command, when value is more than 100 −call showMessage(200, 'John');This will produce ...
Read MoreMySQL query to perform delete operation where id is the biggest?
You can use ORDER BY DESC command with LIMIT 1 for this since we need to delete only a single ID.Let us first create a table −mysql> create table DemoTable ( UserId int, UserName varchar(20) ); Query OK, 0 rows affected (0.57 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(100, 'John'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(234, 'Mike'); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable values(145, 'Sam'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(278, 'Carol'); Query OK, 1 ...
Read MoreMySQL query to select too many rows?
You can use LIMIT for this, which is used to fetch limited number of records. Let us first create a table −mysql> create table DemoTable ( Id int, Name varchar(20) ); Query OK, 0 rows affected (0.53 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(10, 'John'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(11, 'Chris'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(12, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(13, 'Carol'); Query OK, 1 row affected (0.13 sec) mysql> ...
Read MoreWhich datatype is should I use to set a column for 5-star rating?
You can use ENUM datatype for this. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserRating ENUM('1', '2', '3', '4', '5') ); Query OK, 0 rows affected (0.54 sec)Insert records in the table using insert command −mysql> insert into DemoTable(UserRating) values('5'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(UserRating) values('3'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(UserRating) values('1'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(UserRating) values('3'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable(UserRating) values('4'); ...
Read MoreReplace dot with comma on MySQL SELECT?
To replace dot with comma on SELECT, you can use REPLACE(). Following is the syntax −select replace(yourColumnName, '.' , ', ' ) from yourTableName;Let us first create a table −mysql> create table DemoTable ( Value float ); Query OK, 0 rows affected (0.63 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(4.56); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(456.23); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(1078.3); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values(2000.50); Query OK, 1 row affected (0.26 sec) mysql> ...
Read MoreHow to select from a set of integers in MySQL?
To select from a set of integers, you can use UNION. Following is the syntax −SELECT yourValue1 UNION SELECT yourValue2 UNION SELECT yourValue3 UNION SELECT yourValue4 . . . . NLet us implement the above syntax to select from a set of integers in MySQL −mysql> SELECT 1000 UNION SELECT 2000 UNION SELECT 3000 UNION SELECT 4000 UNION SELECT 5000 UNION SELECT 6000 UNION SELECT 7000;This will produce the following output −+------+ | 1000 | +------+ | 1000 | | 2000 | | 3000 | | 4000 | | 5000 | | 6000 | | 7000 | +------+ 7 rows in set (0.03 sec)
Read MoreHow to remove Duplicate Records except a single record in MySQL?
You can use DELETE command with some condition for this since we need to keep one record and delete rest of the duplicate records.Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(40) ); Query OK, 0 rows affected (0.48 sec)Insert records in the table using insert command −mysql> insert into DemoTable(StudentName) values('John'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(StudentName) values('Carol'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(StudentName) values('Sam'); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable(StudentName) ...
Read MoreMySQL order by from highest to lowest value?
To order by from highest to lowest value, you can use ORDER BY DESC command −select *from yourTableName order by yourColumnName DESC;If you want the result from lowest to highest, you can use ORDER BY ASC command −select *from yourTableName order by yourColumnName ASC;Let us first create a table −mysql> create table DemoTable ( Value int ); Query OK, 0 rows affected (0.56 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(134); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(245); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable ...
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