Database Articles

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Update record on a specific date matching the current date in MySQL

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 794 Views

Let us first create a table −mysql> create table DemoTable1822      (      Amount int,      DueDate date      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1822 values(1000, '2019-10-11'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1822 values(500, '2019-11-30'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1822 values(700, '2018-11-30'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1822;This will produce the following output −+--------+------------+ | Amount | ...

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Will MySQL work if we won't include the size of VARCHAR while creating a new table?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 171 Views

No, the query won’t work. Let’s create the same scenario and check the error −mysql> create table DemoTable1821      (      Id int,      FirstName varchar,      LastName varchar      ); ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ', LastName varchar )' at line 4To remove the above error, you need to give the size of varchar(10). Let us first create a table −mysql> create table DemoTable1821      (      Id int, ...

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MySQL query to subtract date records with week day and display the weekday with records

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 268 Views

For this, you can use DATE_FORMAT(). Let us first create a table −mysql> create table DemoTable1820      (      AdmissionDate varchar(20)      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1820 values('20/10/2019'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1820 values('19/12/2018'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1820 values('16/04/2017'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1820;This will produce the following output −+---------------+ | AdmissionDate | +---------------+ ...

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Count the same value of each row in a MySQL column?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 433 Views

To count the same value of each row, use COUNT(*) along with GROUP BY clause. Let us first create a table −mysql> create table DemoTable1818      (      Id int,      Name varchar(20)      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1818 values(10, 'Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1818 values(11, 'Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1818 values(11, 'Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1818 values(12, 'Chris'); Query ...

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Passing Multiple ids to single parameter in MySQL?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 1K+ Views

To pass multiple ids to single parameter, use FIND_IN_SET(). Let us first create a table −mysql> create table  DemoTable1817      (      EmployeeName varchar(20),      CountryName varchar(20)      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1817 values('Chris', 'AUS'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1817 values('David', 'UK'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1817 values('Bob', 'US'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1817;This ...

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MySQL randomly select 2 values from column values?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 427 Views

To randomly select, use ORDER BY RAND(). To select only 2 values, use LIMIT 2 in MySQL. Let us first create a table −mysql> create table DemoTable1815      (      Question text      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1815 values('What is your name?'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1815 values('What is your college name?'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1815 values('What is your nick name?'); Query OK, 1 row affected (0.00 sec) mysql> ...

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Implement and set DOUBLE length in MySQL

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 545 Views

To implement DOUBLE in MySQL, the syntax is as follows −create table yourTableName      (      yourColumnName double(5, 2) unsigned );Let us first create a table −mysql> create table DemoTable1814      (      Amount double(5, 2) unsigned      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1814 values(1.98); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1814 values(100.24); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1814 values(198.50); Query OK, 1 row affected (0.00 sec)Display all records from the table ...

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How to GRANT SELECT ON all tables in all databases on a server with MySQL?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 1K+ Views

For this, you can use GRANT SELECT statement as in the below syntax −GRANT SELECT ON *.* TO 'yourUserName'@'yourHostName';First list all the user names along with host −mysql> select user, host from mysql.user;This will produce the following output −+------------------+-----------+ | user             |      host | +------------------+-----------+ | Bob              |         % | | Charlie          |         % | | Robert           |         % | | User2       ...

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How to select and display a list of values in one column that are available in two different MySQL columns?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 2K+ Views

For this, use UNION ALL. Let us first create a table −mysql> create table DemoTable1813      (      Name1 varchar(20),      Name2 varchar(20)      ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1813 values('John', 'Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1813 values('Adam', 'Robert'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1813 values('Mike', 'Sam'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1813;This will produce the following ...

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How to extract column name and type from MySQL?

AmitDiwan
AmitDiwan
Updated on 24-Dec-2019 540 Views

To extract column name and type, use INFORMATION_SCHEMA.COLUMNS −select concat(column_name, '=', data_type) as anyAliasName from information_schema.columns where table_schema= yourDatabaseName and table_name= yourTableName;Let us first create a table −mysql> create table DemoTable1812      (      Id int,      FirstName varchar(20),      Age int,      isMarried boolean,      status ENUM('ACTIVE', 'INACTIVE')      ); Query OK, 0 rows affected (0.00 sec)Here is the query to extract column name and type from MySQL:mysql> select concat(column_name, '=', data_type) as COLUMNNAMEANDTYPE from information_schema.columns      where table_schema= 'web' and table_name= 'DemoTable1812';This will produce the following output −+-------------------+ | COLUMNNAMEANDTYPE ...

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