Found 4378 Articles for MySQL

MySQL select order by acts like a string (not a number)?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

155 Views

You can use the following syntax if your column has varchar data type −select yourColumnName FROM yourTableName ORDER BY yourColumnName +0 DESC;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectOrderdemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(100),    -> RankNumber varchar(100)    -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into selectOrderdemo(Name, RankNumber) values('Larry', -100); Query OK, 1 row affected (0.23 ... Read More

Deleting all rows older than 5 days in MySQL

Naveen Singh
Updated on 30-Jul-2019 22:30:25

1K+ Views

To delete all rows older than 5 days, you can use the following syntax −delete from yourTableName    where datediff(now(), yourTableName.yourDateColumnName) > 5;Note − Let’s say the current date is 2019-03-10.To understand the concept, let us create a table. The query to create a table is as follows −mysql> create table deleteRowsOlderThan5Demo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(100),    -> Post_Date date    -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into deleteRowsOlderThan5Demo(Name, Post_Date) ... Read More

How to remove hyphens using MySQL UPDATE?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

689 Views

To remove hyphens using MySQL update, you can use replace() function. The syntax is as follows −update yourTableName    set yourColumnName=replace(yourColumnName, '-', '' );To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table removeHyphensDemo    -> (    -> userId varchar(100)    -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into removeHyphensDemo values('John-123-456'); Query OK, 1 row affected (0.22 sec) mysql> insert into removeHyphensDemo values('Carol-9999-7777-66555'); Query OK, 1 row affected (0.19 sec) ... Read More

Count top 10 most occurring values in a column in MySQL?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

1K+ Views

To count the top 10 most occurring values in a column in MySQL, The syntax is as follows −SELECT yourColumnName, count(*)    FROM yourTableName    GROUP BY yourColumnName    ORDER BY count(*) DESC    LIMIT 10;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table countTop10Demo    -> (    -> Value int    -> ); Query OK, 0 rows affected (0.74 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into countTop10Demo values(10); Query OK, 1 row affected (0.12 sec) ... Read More

MySQL select dates in 30-day range?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

1K+ Views

To select dates in 30-day range, you can use arithmetic operation - with interval.The syntax is as follows −select *from yourTableName where yourDateColumnName > NOW() - INTERVAL 30 DAY and yourDateColumnName < NOW() + INTERVAL 30 DAY;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectDatesDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> ArrivalDate datetime    -> ); Query OK, 0 rows affected (0.77 sec)Now you can insert some records in the table using insert command. The query is as ... Read More

Use JOIN to select record with more than one condition using AND?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

96 Views

Let us first create a demo table −mysql> create table selectPerson    -> (    -> PersonId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> PersonName varchar(20),    -> PersonFavouriteFruit varchar(60)    -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into selectPerson(PersonName, PersonFavouriteFruit) values('John', 'Banana'); Query OK, 1 row affected (0.14 sec) mysql> insert into selectPerson(PersonName, PersonFavouriteFruit) values('John', 'Blackberry'); Query OK, 1 row affected (0.12 sec) mysql> insert into selectPerson(PersonName, PersonFavouriteFruit) values('John', 'Blueberry'); Query OK, 1 row affected (0.12 sec) mysql> insert into selectPerson(PersonName, ... Read More

Does MySQL eliminate common subexpressions between SELECT and HAVING/GROUP BY clause? How to test it?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

43 Views

To test, use the sleep() function.Case 1 −The syntax is as follows −SELECT yourColumnName+sleep(yourIntegerValue) FROM yourTableName GROUP BY yourColumnName+sleep(yourIntegerValue);;Case 2 − You can use another syntax which is as follows −SELECT yourColumnName+sleep(yourIntegerValue) As anyAliasName FROM yourTableName GROUP BY yourAliasName;To understand the above syntaxes, let us create a table. The query to create a table is as follows −mysql> create table sleepDemo    -> (    -> value int    -> ); Query OK, 0 rows affected (1.25 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into sleepDemo values(40); Query OK, 1 row ... Read More

Is it possible to have View and table with the same name in MySQL?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

1K+ Views

No, you cannot give the same name for view and table in MySQL.Let us first create a demo table −mysql> create table view_Table_Demo    -> (    -> Id int,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (0.80 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into view_Table_Demo values(100, 'Larry'); Query OK, 1 row affected (0.17 sec) mysql> insert into view_Table_Demo values(101, 'Mike'); Query OK, 1 row affected (0.20 sec) mysql> insert into view_Table_Demo values(102, 'Sam'); Query OK, 1 row affected (0.14 sec)Display all ... Read More

MySQL server version for the right syntax to use near 'OPTION SQL_SELECT_LIMIT=10'?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

672 Views

You can use SET command, but SET OPTIOn deprecated. Therefore, use SET SQL_SELECT_LIMIT.The syntax is as follows −SET SQL_SELECT_LIMIT=yourIntegerValue;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table MySQLSelectDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY    -> ); Query OK, 0 rows affected (0.99 sec)Insert some records in the table using insert command. The query is as follows −mysql> INSERT INTO MySQLSelectDemo VALUES(), (), (), (), (), (), (), (), (), (), (), (), (), (), (), (), (), (), (), (), ... Read More

How do I delete blank rows in MySQL?

Naveen Singh
Updated on 30-Jul-2019 22:30:25

22K+ Views

Use the delete command to delete blank rows in MySQL.The syntax is as followsdelete from yourTableName where yourColumnName=' ' OR yourColumnName IS NULL;The above syntax will delete blank rows as well as NULL row.To understand the concept, let us create a table.The query to create a table is as followsmysql> create table deleteRowDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> StudentName varchar(20)    -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into deleteRowDemo(StudentName) values('John'); Query OK, 1 row affected ... Read More

Advertisements