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MySQL Articles
Page 140 of 355
Display first non-null values with coalesce() in MySQL?
The coalesce() can be used to print first NOT NULL column value. Let us first create a table −mysql> create table DemoTable1927 ( StudentName varchar(20), StudentSubject varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1927 values('Chris', 'MySQL'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1927 values('David', NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1927 values(NULL, 'MongoDB'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1927;This will ...
Read MoreHow to select rows if initial ones are randomized and the rest ordered by criteria with MySQL?
For this, you can use ORDER BY CASE statement. Let us create a table −mysql> create table DemoTable1926 ( Position varchar(20), Number int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1926 values('Highest', 50); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1926 values('Highest', 30); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1926 values('Lowest', 100); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1926 values('Lowest', 120); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1926 values('Lowest', ...
Read MoreHow to update a specific column value fetched with CASE statement?
For this, use UPDATE command along with CASE statement. Let us first create a table −mysql> create table DemoTable1925 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(20), StudentMarks int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1925(StudentName, StudentMarks) values('Chris', 98); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1925(StudentName, StudentMarks) values('David', 45); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1925;This will produce the following output −+-----------+-------------+--------------+ | ...
Read MoreUpdate the records in a table with a specific year fetched from date format like '10/12/2010'?
To update records with a specific year, use the YEAR() method as in the below syntax:update yourTableName set yourColumnName1=yourValue1 where YEAR(str_to_date(yourColumnName2, '%d/%m/%Y'))=yourValue2;Let us first create a table −mysql> create table DemoTable1924 ( UserName varchar(20), UserJoiningDate varchar(40) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1924 values('Chris', '10/12/2010'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1924 values('David', '20/01/2011'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1924 values('Mike', '20/01/2010'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1924 values('Carol', ...
Read MoreFix a specific column value and display random values for rest of the rows in MySQL
For random rows, you can use RAND(), whereas to fix a specific column, use ORDER BY clause. Let us create a table −mysql> create table DemoTable1921 ( Number int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1921 values(40); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1921 values(80); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1921 values(820); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1921 values(10); Query OK, 1 row affected (0.00 sec)Display all records from the ...
Read MoreGroup the marks of a particular student from a table and display total marks in a separate column for each student?
To group marks, use MySQL GROUP BY. To sum, use MySQL sum()function. Let us first create a table −mysql> create table DemoTable1920 ( StudentName varchar(20), StudentMarks int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1920 values('Chris', 67); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1920 values('David', 97); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1920 values('Chris', 57); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1920 values('David', 45); Query OK, 1 row affected (0.00 sec) mysql> ...
Read MoreFix: ERROR 1396 (HY000): Operation CREATE USER failed in MySQL?
To fix the error, let us see how to create a user correctly. Let us create a user −mysql> create user 'Emma'@'localhost' IDENTIFIED BY 'emma_654'; Query OK, 0 rows affected (0.00 sec)Let us display all users along with host −mysql> select user, host from MySQL.user;This will produce the following output. The new user created above is visible in the below list of all users along with host −+------------------+-----------+ | user | host | +------------------+-----------+ | Bob | % | | Charlie ...
Read MoreQuery the database for the values not in the MySQL table?
For this, you can use UNION ALL along with WHERE NOT EXISTS and implement NOT IN to ignore the values already in the table. Use SELECT with UNION ALL to add values not already in the table.Let us first create a table −mysql> create table DemoTable1918 ( Value int NOT NULL AUTO_INCREMENT PRIMARY KEY ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1918 values(); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1918 values(); Query OK, 1 row affected (0.00 sec) mysql> insert into ...
Read MoreGet all rows apart from first and last in MySQL
To get all rows apart from first and last, use subquery along with MIN() and MAX(). Let us first create a table −mysql> create table DemoTable1917 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentCode int, StudentMarks int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1917(StudentCode, StudentMarks) values(78, 95); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1917(StudentCode, StudentMarks) values(78, 96); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1917(StudentCode, StudentMarks) values(78, 97); Query OK, 1 row affected (0.00 ...
Read MoreWrite MySQL case statement to set custom messages for student's result
For this, set conditions using MySQL CASE statement −mysql> create table DemoTable1916 ( StudentName varchar(20), StudentMarks int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1916 values('Chris', 59); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1916 values('David', 89); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1916 values('Sam', 94); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1916 values('Mike', 75); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1916 values('Carol', 69); Query OK, 1 row affected ...
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