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Articles on Trending Technologies
Technical articles with clear explanations and examples
MySQL query to display only the empty and NULL values together?
To check for NULL, use the IS NULL. For empty values, you need to check with an empty string. We will now see an example.Let us first create a table −mysql> create table DemoTable691( PlayerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, PlayerName varchar(100), PlayerScore int ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable691(PlayerName, PlayerScore) values('Robert', 56); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable691(PlayerName, PlayerScore) values('David', 89); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable691(PlayerName, PlayerScore) values('', 98); Query ...
Read MoreWill "create table table" work in MySQL since we cannot use reserved words as table name?
Let us first see a case wherein we use “create table table” while creating a table. An error will arise −mysql> create table table( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100) );This will produce the following output i.e. error −ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'table( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100) )' at line 1As you can see above, the word “table” is a reserved keyword, and we ...
Read MoreHow to select records that begin with a specific value in MySQL?
To select records that begin with a specific value, you need to use LIKE operator. Let us first create a table −mysql> create table DemoTable690( UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserValue varchar(100) ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable690(UserValue) values('567890'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable690(UserValue) values('789032'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable690(UserValue) values('567342'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable690(UserValue) values('890678'); Query OK, 1 row affected (0.16 sec)Display ...
Read MoreHow to find missing value between two MySQL Tables?
To find missing value between two MySQL tables, use NOT IN. Let us first create a table −mysql> create table DemoTable1(Value int); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(1); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1 values(2); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable1 values(5); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable1 values(6); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable1 values(8); Query OK, 1 row affected (0.16 sec)Display all records from ...
Read MoreMySQL query to insert data from another table merged with constants?
Let us first create a table −mysql> create table DemoTable1(Name varchar(100)); Query OK, 0 rows affected (0.83 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values('John'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1 values('Chris'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1 values('Robert'); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable1;This will produce the following output −+--------+ | Name | +--------+ | John | | Chris | | Robert | +--------+ 3 ...
Read MoreWorking with MySQL WHERE.. OR query with multiple OR usage. Is there an alternative?
Yes, an alternative for MySQL “WHERE.. OR” is using REGEXP.Let us first create a table −mysql> create table DemoTable684(EmployeeInformation text); Query OK, 0 rows affected (0.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable684 values('John 21 Google'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable684 values('Carol 23 Amazon'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable684 values('Carol 26 Flipkart'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable684 values('David 29 Microsoft'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> ...
Read MoreUse NOT IN, OR and IS NULL in the same MySQL query to display filtered records
Let us first create a table −mysql> create table DemoTable793( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(100) ); Query OK, 0 rows affected (0.81 sec)Insert some records in the table using insert command −mysql> insert into DemoTable793(StudentName) values('Adam'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable793(StudentName) values('Bob'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable793(StudentName) values(null); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable793(StudentName) values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable793(StudentName) values('Robert'); Query OK, 1 row affected (1.03 sec)Display all records from ...
Read MoreConcatenate string with numbers in MySQL?
To concatenate string with numbers, use the CONCAT() method. Let us first create a table −mysql> create table DemoTable682( Name varchar(100), Age int ); Query OK, 0 rows affected (0.49 sec)Insert some records in the table using insert command −mysql> insert into DemoTable682 values('John', 23); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable682 values('Chris', 21); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable682 values('David', 25); Query OK, 1 row affected (0.17 sec) Display all records from the table using select statement:Display all records from the table using select statement -mysql> select *from ...
Read MoreHow to order return duplicate column values only once in MySQL?
To return a column value only once in MySQL, let us first see an example and create a table −mysql> create table DemoTable680(Status varchar(100)); Query OK, 0 rows affected (0.75 sec)Insert some records in the table using insert command −mysql> insert into DemoTable680 values('Busy'); Query OK, 1 row affected (0.36 sec) mysql> insert into DemoTable680 values('At Work'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable680 values('Busy'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable680 values('Blocked'); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable680 values('Offline'); Query OK, 1 row affected (0.67 sec) ...
Read MoreHow to order records and fetch some using MySQL LIMIT?
Let us first create a table −mysql> create table DemoTable679(FirstName varchar(100)); Query OK, 0 rows affected (0.44 sec)Insert some records in the table using insert command −mysql> insert into DemoTable679 values('John'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable679 values('Chris'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable679 values('David'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable679 values('Bob'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable679 values('Mike'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable679 values('Sam'); Query OK, 1 row affected (0.15 sec) mysql> insert ...
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