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Database Articles
Page 411 of 547
Selecting all the users with maximum age values using a MySQL subquery?
Let us first create a table −mysql> create table DemoTable ( Name varchar(100), Age int ); Query OK, 0 rows affected (0.46 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 23); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('David', 55); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Bob', 53); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Mike', 54); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values('Sam', 55); Query OK, 1 row affected (0.18 sec)Display all records ...
Read MoreHow to remove duplicate values from a MySQL table using LEFT JOIN?
Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100) ); Query OK, 0 rows affected (0.46 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(FirstName) values('Chris'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(FirstName) values('Robert'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(FirstName) values('Robert'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(FirstName) values('John'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(FirstName) values('John'); Query OK, 1 row affected (0.11 sec) mysql> insert ...
Read MoreHow to concatenate strings from different columns and an additional string using a MySQL query?
Let us first create a table −mysql> create table DemoTable ( FirstName varchar(100), LastName varchar(100) ); Query OK, 0 rows affected (0.76 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 'Brown'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Adam', 'Smith'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Carol', 'Taylor'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('David', 'Miller'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the ...
Read MoreHow to update a field with a particular value if it is null in MySQL?
To update a field if it is null, use IS NULL property along with the UPDATE command. Let us first create a table −mysql> create table DemoTable ( StudentScore int ); Query OK, 0 rows affected (0.47 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(89); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(NULL); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(45); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values(NULL); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(56); ...
Read MoreInsert values from the first table to the second table using two SELECT statements in a single MySQL query
To insert values from the first table to another table using two SELECT statements, use SUBQUERY. This will allow you to use only a single MySQL query to get the result in the second table. Let us first create a table −mysql> create table DemoTable1 ( Name varchar(100), Score int ); Query OK, 0 rows affected (1.30 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values('Chris', 45); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1 values('Bob', 78); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1 values('David', 98); ...
Read MoreHow to ORDER BY FIELD with GROUP BY in a single MySQL query?
For this, let us first create a table −mysql> create table DemoTable ( Message text ); Query OK, 0 rows affected (1.15 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Good'); Query OK, 1 row affected (0.43 sec) mysql> insert into DemoTable values('Bye'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Awesome'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Bye'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable values('Good'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values('Amazing'); Query OK, 1 ...
Read MoreHow to set MySQL default value NONE?
To set the default value in MySQL, you need to use the DEFAULT keyword. Let us first create a table −mysql> create table DemoTable ( ClientCountryName varchar(100) DEFAULT 'NONE' ); Query OK, 0 rows affected (0.65 sec)We have set DEFAULT above for values not entered while insertion. Now, let us insert some records in the table using the insert command. We haven’t inserted values here for some of the rows. The DEFAULT gets set there −mysql> insert into DemoTable values('US'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(); Query OK, 1 row affected (0.09 sec) ...
Read MoreCan we use SELECT NULL statement in a MySQL query?
Yes, we can use the SELECT NULL statement in a MySQL query. Let us first create a table −mysql> create table DemoTable ( Name varchar(100) ); Query OK, 0 rows affected (0.49 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.47 sec) mysql> insert into DemoTable values('Mike'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values('Sam'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Bob'); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected ...
Read MoreUpdate only a single value from a MySQL table where select from same table ordered in descending order?
For this, use ORDER BY DESC with the LIMIT clause. The ORDER BY DESC order in descending order where LIMIT sets the number of records you want. Here, we will set LIMIT 1 since we want only a single record. Let us first create a table −mysql> create table DemoTable ( StudentName varchar(100), StudentMarks int ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 45); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('Bob', 78); Query OK, 1 row affected (0.16 sec) mysql> ...
Read MoreReturn true or false in a MySQL select if another field contains a string?
To return TRUE or FALSE if another field contains a string, use IF(). Let us first create a tablemysql> create table DemoTable ( FirstName varchar(100), LastName varchar(100) ); Query OK, 0 rows affected (1.28 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 'Brown'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('David', 'Miller'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Adam', 'Smith'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following ...
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