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MySQL Articles
Page 294 of 355
MySQL UPDATE using IF condition
The syntax is as follows to perform UPDATE using IF condition in MySQL −update yourTableName set yourColumnName =if(yourColumnName =yourOldValue, yourNewValue, yourColumnName);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table updateIfConditionDemo -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserName varchar(20), -> UserAge int -> ); Query OK, 0 rows affected (4 min 0.59 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into updateIfConditionDemo(UserName, UserAge) values('Larry', 23); Query OK, ...
Read MoreFind minimum unused value in a MySQL table?
You can use LEFT JOIN to find minimum unused value in a MySQL table. Let us first create a tablemysql> create table FindValue -> ( -> SequenceNumber int -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into FindValue values(109); Query OK, 1 row affected (0.14 sec) mysql> insert into FindValue values(110); Query OK, 1 row affected (0.15 sec) mysql> insert into FindValue values(111); Query OK, 1 row affected (0.13 sec) mysql> insert into FindValue values(113); Query OK, 1 row affected (0.13 ...
Read MoreCan't find my.ini in MySQL directory?
The my.ini is in hidden folder of program data. First go to C: drive and then hidden folder of program data. From that, move to the MySQL version directory.Here is the snapshot of the C: drive −Click on C drive. The snapshot is as follows. Here, you can see the Program Data folder −Now go to MySQL under Program Data folder. The snapshot is as follows −Go to MySQL version. The snapshot is as follows −Note − Here, we are using MySQL version 8.0.12Here is the my.ini file.In order to reach the location, you can also use the following command ...
Read MoreBest way to store weekly event in MySQL?
Let us see the best way to store weekly events in MySQL. For that, first create a new table and include fields for every day as well.mysql> create table WeeklyEventDemo -> ( -> ID int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EventName varchar(20), -> Monday tinyint(1), -> Tuesday tinyint(1), -> Wednesday tinyint(1), -> Thursday tinyint(1), -> Friday tinyint(1), -> Saturday tinyint(1), -> Sunday tinyint(1), -> StartDate date, ...
Read MoreMySQL appears to DROP USER but user still exists in MySQL.users table?
First check all the user and host from MySQL.user table with the help of select statement as shown belowmysql> select user, host from MySQL.user;The following is the output+------------------+-----------+ | user | host | +------------------+-----------+ | Bob | % | | Manish | % | | User2 | % | | mysql.infoschema | % | | mysql.session | % ...
Read MoreHow to change MySQL error message language?
You can use lc_messages to change MySQL error message language. The syntax is as follows −SET lc_messages = 'yourLanguage';To understand the concept, let us create a table with some error and check the error message language.Here, we have set the local message to French. Let us first create a table −mysql> create table errorMessagelanguage -> ( -> Error_MessageId int, -> Error_Message varchar(100), -> );The error message is as follows −ERROR 1064 (42000): Erreur de syntaxe près de ')' à la ligne 5Now you can set the error message to be in English language. The query is ...
Read MoreConvert PHP variable "11:00 AM" to MySQL time format?
Use DateTime to convert PHP variable “11:00 AM: to MySQL time format.The PHP code is as follows −$phpTime = '11:00 AM'; echo('The PHP Time Format is ='); echo ($phpTime); $timeFormat = DateTime::createFromFormat( 'H:i A', $phpTime); $MySQLTimeFormat = $timeFormat->format( 'H:i:s'); echo (' '); echo('The MySQL Time Format is ='); echo ($MySQLTimeFormat);The snapshot of PHP code is as follows −Here is the output −The PHP Time Format is =11:00 AM The MySQL Time Format is =11:00:00
Read MoreReturn null for date_format when input is null in MySQL?
Use IF() function to return null for date_format when input is null in MySQL. The syntax is as follows −SELECT IF(yourDateColumnName, date_format(yourDateColumnName, '%d/%m/%Y'), NULL) FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table returnNullWhenInputIsNullDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ShippingDate datetime -> ); Query OK, 0 rows affected (1.21 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into returnNullWhenInputIsNullDemo(ShippingDate) values('2019-01-21'); Query OK, 1 row affected ...
Read MoreQuery with values prepended by ampersand works in Oracle but not in MySQL?
Ampersands work in Oracle. To work it in MySQL, use @ as shown in the following syntax −SET @yourVariableName1 = yourValue, @yourVariableName2 = yourValue, @yourVariableName3 =yourValue, .........N; insert into yourTableName values(@yourVariableName1, @yourVariableName2, @yourVariableName3, ........N);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table Student_Information -> ( -> StudentId int, -> StudentName varchar(100), -> StudentAge int, -> StudentMarks int, -> StudentCountryName varchar(10) -> ); Query OK, 0 rows affected (0.75 sec)Here is the query with values prepended by @. Insert some records ...
Read MoreVerify that MySQL SET FOREIGN KEY CHECKS is set to = 1?
You can verify SET FOREIGN KEY CHECKS is set to = 1 or not with the help of variable@@foreign_key_checks;The syntax is as follows −select @@foreign_key_checks;You can use SHOW VARIABLES command. The syntax is as follows −show variables like 'foreign%';Now you can implement both the syntaxes.Case 1 − Using variable @@foreign_key_checks.The query is as follows −mysql> SELECT @@foreign_key_checks; Here is the output −+----------------------+ | @@foreign_key_checks | +----------------------+ | 1 | +----------------------+ 1 row in set (0.00 sec)Case 2 − Using SHOW commandThe ...
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