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Database Articles
Page 518 of 547
How to perform Increment in MySQL Update?
To update values incrementally in MySQL, you need to create a variable with the help of SET command. The syntax to create a variable is as follows −set @anyVariableName := 0;To update value, you need to use UPDATE command. Let us begin with creating a table. The query to create a table −mysql> create table UpdateValueIncrementally −> ( −> ProductId int −> ); Query OK, 0 rows affected (0.90 sec)Insert records in the table with the help of select statement. The query is as follows −mysql> insert into UpdateValueIncrementally values(10); Query ...
Read MoreSHOW TABLE statement with multiple LIKE values in MySQL?
You can use WHERE clause and OR operator to show table with multiple LIKE. The syntax is as follows:show table from yourDatabaseName where tables_in_yourDatabaseName Like ‘%anyTableName%’ or tables_in_yourDatabaseName Like ‘%anyTableName2%’ or tables_in_yourDatabaseName Like ‘%anyTableName3%’ . . . . or tables_in_yourDatabaseName Like ‘%anyTableNameN%’In the above syntax, only the table name in the database is displayed.Here the database ‘test’ and the tables in the same database is considered. The query to show tables with multiple LIKE is as follows -mysql> show tables from test -> where tables_in_test like '%userrole%' -> or tables_in_test like '%view_student%' -> or tables_in_test like '%wholewordmatchdemo%';The following is the ...
Read MoreHow to make MySQL's NOW() and CURDATE() functions use UTC?
To make MySQL’s NOW() and CURDATE() functions use UTC, you need to write my.cnf file. Write the below instruction in my.cnf −[mysqld_safe] timezone = UTCFirstly, reach the directory with the help of the following query −mysql> select @@datadir;The following is the output −+---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ 1 row in set (0.00 sec)Now reach the directory for which the link ...
Read MoreMySQL BigInt zerofill vs int zerofill?
The difference between MySQL BigInt and int is that INT is a 32-bit long while BIGINT is 64-bit long.The following are some of the points −The BigInt takes 8 bytes of storage while int takes 4 bytes of storage.The int takes 4294967295 maximum values for int(10), whereas 18, 446, 744, 073, 709, 551, 615 for the bigint(20).The BigInt(20) and int(10), in this 20 and 10 can be used for width display with zerofill.Here is the demo of Bigint and int with zerofill. The following is the query to create a table.mysql> create table BigintandintDemo −> ( ...
Read MoreSetting similar value for a column in a MySQL table?
You can set value for a column of all records with the help of update command.The syntax is as follows if you want set NULL value for all the records in a column −update yourTableName set yourColumnName = NULL;Or if you want to use empty string, the following is the syntax −update yourTableName set yourColumnName = ’’;To understand the above concept, let us create a table. The query to create a table.mysql> create table StudentDemo −> ( −> Studentid int, −> StudentName varchar(100), −> Age int −> ); Query OK, 0 rows affected (0.64 sec)The ...
Read MoreHow to insert multiple rows with single MySQL query?
You can insert multiple rows with the help of values() separated by comma(, ). The syntax is as follows −insert into yourTableName values(value1, value2, ...N), (value1, value2, ...N), (value1, value2, ...N), (value1, value2, ...N), (value1, value2, ...N), (value1, value2, ...N)................N;To insert multiple rows, let us create a table. The following is the query to create a table −mysql> create table MultipleRowsInsert −> ( −> UserId int, −> UserName varchar(200) −> ); Query OK, 0 rows affected (1.21 sec)Here is the query to insert multiple rows in the table −mysql> insert into MultipleRowsInsert values(100, 'Bob'), (101, 'Smith'), ...
Read MoreHow to select an empty result set in MySQL?
Select an empty result set with the help of dummy table ‘dual’ from MySQL. The query is as follows −mysql> select 1 from dual where false; Empty set (0.00 sec)In the above query, “dual” is a dummy table and the above condition false. Therefore, it returns empty set.Let us check with true condition. It will return the selected value. The query is as follows −mysql> select 1 from dual where true;The following is the output −+---+ | 1 | +---+ | 1 | +---+ 1 row in set (0.00 sec)
Read MoreWhat is the Maximum Value of smallint(6) unsigned in MySQL?
The maximum value of SMALLINT(6) unsigned in MySQL is 65535. The number 6 does not affect the actual range. It can only be used to display width on the command line.The Minimum Value signed is-32768The Maximum Value unsigned is65535The Maximum value signed is32767Let us understand this with zerofill and create a table using the following query.mysql> create table smallIntDemo -> ( -> FirstNumber smallint(6) zerofill -> ); Query OK, 0 rows affected (1.95 sec)Now you can insert records in the table using insert command. Whenever you insert beyond the range 65535, it will not insert in the table, since this ...
Read MoreEasy way to re-order columns in MySQL?
To re-order columns in MySQL, use the ALTER TABLE MODIFY COLUMN. The syntax is as follows -ALTER TABLE yourTableName MODIFY COLUMN yourColumnName data type after yourColumnName.To understand the above syntax, let us first create a table. The query to create a table is as follows.mysql> create table reOrderColumn -> ( -> ProductId int, -> DeliveryDate datetime, -> ProductName varchar(100) -> ); Query OK, 0 rows affected (0.76 sec)Now check the description of the table. The query is as follows.mysql> desc reOrderColumn;The following is the output.+--------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ...
Read MoreHow to check multiple columns for a single value in MySQL?
You can check multiple columns for one value with the help of IN operator. The syntax is as follows −select *from yourTableName where value IN(yourColumnName1, yourColumnName2, ......N);To understand the above concept, let us create a table with some columns. The query to create a table is as follows −mysql> create table OneValueFromAllColumns −> ( −> StudentId int, −> StudentFirstname varchar(200), −> StudentLastname varchar(200), −> StudentAge int −> ); Query OK, 0 rows affected (1.41 sec)Insert some records in the table with the ...
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