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MySQL Articles
Page 242 of 355
MySQL query to select bottom n records
Let us first create a table −mysql> create table DemoTable724 (Value int); Query OK, 0 rows affected (0.79 sec)Insert some records in the table using insert command −mysql> insert into DemoTable724 values(101); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable724 values(183); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable724 values(983); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable724 values(234); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable724 values(755); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable724 values(435); Query OK, 1 row affected (0.28 sec) mysql> ...
Read MoreSelect a value from MySQL database only if it exists only once from a column with duplicate and non-duplicate values
Let us first create a table −mysql> create table DemoTable723 (Value int); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable723 values(100); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable723 values(200); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable723 values(200); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable723 values(100); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable723 values(300); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable723 values(400); Query OK, 1 row affected (0.16 sec) mysql> ...
Read MoreREGEX in MySQL to display only numbers separated by hyphen.
Let us first create a table −mysql> create table DemoTable ( Code varchar(100) ); Query OK, 0 rows affected (1.16 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('100-677-9876'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('100-677-9876-John'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('David-100-677-9876'); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+--------------------+ | Code | +--------------------+ ...
Read MoreIs there a way to list all the reserved words in MySQL using the MySQL command-line utility?
Yes, we can all the reserved words in MySQL using the command-line utility. Following is the syntax −select *from mysql.help_keyword;Let us implement the above syntax in order to get list of all the reserved words in MySQL.Following is the query −mysql> select *from mysql.help_keyword;This will produce the following output -
Read MoreDELETE from MySQL table WHERE column equals value AND column2 equals value2?
Let us first create a table −mysql> create table DemoTable722 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(100), StudentAge int ); Query OK, 0 rows affected (1.84 sec)Insert some records in the table using insert command −mysql> insert into DemoTable722(StudentName, StudentAge) values('Chris Brown', 23) ; Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable722(StudentName, StudentAge) values('John Smith', 21); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable722(StudentName, StudentAge) values('David Miller', 22); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable722(StudentName, StudentAge) values('Adam Smith', 20); Query OK, 1 row affected ...
Read MoreIs there such thing as a SELECT with an IF/ELSE statement in MySQL?
Yes, SELECT with an IF/ELSE is possible in MySQL.Let us first create a table −mysql> create table DemoTable721 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100), Marks int, CountryName varchar(100) ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable721(FirstName, Marks, CountryName) values('Chris', 56, 'US'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable721(FirstName, Marks, CountryName) values('Robert', 78, 'UK'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable721(FirstName, Marks, CountryName) values('Mike', 45, 'AUS'); Query OK, 1 row affected (0.16 sec) ...
Read MorePrevent having a zero value in a MySQL field?
Use trigger BEFORE INSERT on the table to prevent having a zero value in a MySQL field. Let us first create a table −mysql> create table DemoTable(Value int); Query OK, 0 rows affected (0.85 sec)Let us create a trigger to prevent having a zero value in a MySQL field −mysql> DELIMITER // mysql> create trigger preventing_to_insert_zero_value before insert on DemoTable for each row begin if(new.Value = 0) then SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'You can not provide 0 value'; END if; end // Query OK, 0 rows affected (0.34 sec) mysql> DELIMITER ...
Read MoreI used ‘from’ and ‘to’ with backticks as column titles in my database table. Now, how do I SELECT them?
At first, to use reserved words, it should be set with backticks like −`from` `to`Since you want to select the column names set with backtick as shown above, you need to implement the following −select `to`, `from` from yourTableName;Let us first create a table with column names as from and to with backticks −mysql> create table DemoTable720 ( `from` date, `to` date ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable720 values('2019-01-21', '2019-07-23'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable720 values('2017-11-01', '2018-01-31'); Query ...
Read MoreWhat does the slash mean in a MySQL query?
The slash means division ( /) in MySQL query. This can be used to divide two numbers. Here, we will see an example to divide numbers from two columns and display result in a new column.Let us first create a table −mysql> create table DemoTable719 ( FirstNumber int, SecondNumber int ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable719 values(20, 10); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable719 values(500, 50); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable719 values(400, 20); ...
Read MoreHow to find all records which are NOT in the set array with MySQL?
For this, you can use NOT IN() function.Let us first create a table −mysql> create table DemoTable718 ( Id int, FirstName varchar(100), Age int ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable718 values(101, 'Chris', 26); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable718 values(102, 'Robert', 24); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable718 values(103, 'David', 27); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable718 values(104, 'Mike', 28); Query OK, 1 row affected (0.19 sec) mysql> ...
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