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MySQLi Articles
Page 267 of 341
Change a MySQL Column datatype from text to timestamp?
To change a MySQL column datatype from text to timestamp, you need to use ALTER command.The syntax is as followsALTER TABLE yourTableName MODIFY COLUMN yourColumnName TIMESTAMP;To understand the above syntax, let us create a table.The query to create a table is as followsmysql> create table textTotimestampdemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Source text - > ); Query OK, 0 rows affected (0.44 sec)Here is the description of table using DESC command.The syntax is as followsDESC yourTableName;The query is as followsmysql> desc textTotimestampdemo;The following is the output+--------+---------+------+-----+---------+----------------+ | ...
Read MoreHow to set two variables in a stored procedure with a single MySQL select statement?
For this, let us first create a new table in MySQLmysql> create table useProcedure - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > FirstName varchar(20), - > LastName varchar(20) - > ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into useProcedure(FirstName, LastName) values('Adam', 'Smith'); Query OK, 1 row affected (0.27 sec)The following is your stored procedure to set two variables in a stored procedure with single select ...
Read MoreHow to implement GROUP by range in MySQL?
To group by range in MySQL, let us first create a table. The query to create a table is as followsmysql> create table GroupByRangeDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > YourRangeValue int - > ); Query OK, 0 rows affected (0.78 sec)Now you can insert some records in the table using insert command.The query is as followsmysql> insert into GroupByRangeDemo(YourRangeValue) values(1); Query OK, 1 row affected (0.14 sec) mysql> insert into GroupByRangeDemo(YourRangeValue) values(7); Query OK, 1 row affected (0.15 sec) mysql> insert into GroupByRangeDemo(YourRangeValue) values(9); Query OK, 1 ...
Read MoreCan we exclude entries with "0" while using MySQL AVG function?
To exclude entries with “0”, you need to use NULLIF() with function AVG().The syntax is as followsSELECT AVG(NULLIF(yourColumnName, 0)) AS anyAliasName FROM yourTableName;Let us first create a tablemysql> create table AverageDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > StudentName varchar(20), - > StudentMarks int - > ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into AverageDemo(StudentName, StudentMarks) values('Adam', NULL); Query OK, 1 row affected (0.12 sec) mysql> insert into AverageDemo(StudentName, StudentMarks) values('Larry', 23); Query OK, ...
Read MoreCalculate total time duration (add time) in MySQL?
To calculate the total time duration in MySQL, you need to use SEC_TO_TIME(). Let us see an example by creating a tablemysql> create table AddTotalTimeDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > LoginTime time - > ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into AddTotalTimeDemo(LoginTime) values('05:05:00'); Query OK, 1 row affected (0.10 sec) mysql> insert into AddTotalTimeDemo(LoginTime) values('07:20:00'); Query OK, 1 row affected (0.16 sec) mysql> insert ...
Read MoreHow to specify exact order with WHERE `id` IN (...) in MySql?
To specify exact order with where id IN, you need to use find_in_set() function.The syntax is as followsSELECT *FROM yourTableName WHERE yourColumnName IN (yourValue1, yourValue2, yourValue3, ....N) ORDER BY FIND_IN_SET(yourColumnName , ‘yourValue1, yourValue2, yourValue3, ....N’');Let us first create a tablemysql> create table FindInSetDemo - > ( - > Id int, - > Name varchar(20), - > Age int - > ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into FindInSetDemo values(10, 'John', 23); Query OK, 1 row affected (0.20 sec) mysql> insert ...
Read MoreFilter the records of current day, month and year in MySQL?
Let’s say you have a table with UserLoginTime column wherein we have stored some values for sample. This is the login time of users and we want to filter all these records on the basis of current day, month and year i.e. the current date. We will beLet us now create the table we discussed abovemysql> create table userLoginInformation - > ( - > UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > UserName varchar(20), - > UserLoginTime datetime - > ); Query OK, 0 rows affected (0.79 sec)Insert some records in the table using ...
Read MoreIs it possible to enforce data checking in MySQL using Regular Expression?
Yes, it is possible to enforce data checking in MySQL using regular expression. First, you need to create a table. After that you need to create a trigger before insert in table. Here, we will be checking the Phone Number format.The query to create a table is as followsmysql> create table enforceDataUsingRegularExpression - > ( - > yourPhoneNumber varchar(60) - > ); Query OK, 0 rows affected (0.59 sec)The query to create a trigger is as followsmysql> DELIMITER // mysql> CREATE TRIGGER enforce_phone_check BEFORE INSERT ON enforceDataUsingRegularExpression - ...
Read MoreAdd a positive integer constraint to an integer column in MySQL?
You need to use unsigned for this because it won’t allow you to enter a negative number.The syntax is as followsCREATE TABLE yourTableName ( yourColumnName INT UNSIGNED );To understand the concept, let us create a table. The query to create a table is as followsmysql> create table OnlyPositiveValue - > ( - > Marks int UNSIGNED - > ); Query OK, 0 rows affected (0.58 sec)Before inserting data in the table, use the below query.The query is as followsmysql> SET @@SESSION.sql_mode = 'STRICT_TRANS_TABLES'; Query OK, 0 rows affected, ...
Read MoreGet the last record from a table in MySQL database with Java?
To get data from MySQL database, you need to use executeQuery() method from java. First create a table in the MySQL database. Here, we will create the following table in the ‘sample’ databasemysql> create table javaGetDataDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > FirstName varchar(10), - > LastName varchar(10) - > ); Query OK, 0 rows affected (0.80 sec)Now you can insert some records in the table using insert command.The query is as followsmysql> insert into javaGetDataDemo(FirstName, LastName) values('John', 'Smith'); Query OK, 1 row affected (0.19 sec) mysql> insert into javaGetDataDemo(FirstName, LastName) values('Carol', ...
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