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Database Articles
Page 407 of 547
How to find a particular varchar id in MySQL from a list of values?
To get a particular varchar ID from a list, you can use FIND_IN_SET(). Let us first create a table −mysql> create table DemoTable ( Id varchar(255) ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('10, 100, 1000'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('101, 120, 2'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('3, 4, 5'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the ...
Read MorePopulate null columns in a MySQL table and set values
For this, you can use IS NULL property. Let us first create a table −mysql> create table DemoTable ( ProductPrice int, ProductQuantity int, TotalAmount int ); Query OK, 0 rows affected (1.22 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ProductPrice, ProductQuantity) values(100, 2); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(ProductPrice, ProductQuantity) values(500, 4); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable(ProductPrice, ProductQuantity) values(1000, 10); Query OK, 1 row affected (0.21 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce ...
Read MoreHow to make a pair of columns unique in MySQL?
To make a pair of columns unique, use UNIQUE with ALTER TABLE command. Following is the syntax −alter table yourTableName add unique yourUniqueName(yourColumnName1, yourColumnName2, ...N);Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentFirstName varchar(100), StudentLastName varchar(100), StudentAge int, StudentPhoneNumber varchar(20) ); Query OK, 0 rows affected (0.81 sec)Following is the query to make a pair of unique columns in MySQL −mysql> alter table DemoTable add unique DemoTable_unique_StudentFirstName_StudentPhoneNumber(StudentFirstName, StudentPhoneNumber); Query OK, 0 rows affected (0.40 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the ...
Read MoreResolve ERROR 1064 (42000) that occurred after using varchar (without providing the size)
Let us first see when this situation can arise. Create a table and set column name with datatype but without the size −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar, LastName varchar ); 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 ', LastName varchar )' at line 4You can correct the above error by providing the size for varchar data type like varchar(100). The same will fix the issue.Let’s fix it ...
Read MoreWhile creating a MySQL table use the reserved keyword 'Key'
To use the reserved keyword ‘Key’, use the concept of the backtick symbol. Here, for our example, I am using the column name key which needs a backtick symbol around the column name.Let us first create a table −mysql> create table DemoTable ( `Key` int ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(101); Query OK, 1 row affected (0.55 sec) mysql> insert into DemoTable values(110); Query OK, 1 row affected (0.28 sec) mysql> insert ...
Read MoreMySQL SUM function to add decimal values
Let us first create a table −mysql> create table DemoTable ( Money DECIMAL(7, 2) ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100.67); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(199.33); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(500); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(400); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(800); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> ...
Read MoreMySQL query to select a record with two exact values?
For this, you can use GROUP BY HAVING clause. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Value int ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Value) values(600); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(Value) values(600); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(Value) values(800); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(Value) values(800); Query OK, 1 row affected (0.09 sec)Display all records from the table ...
Read MoreDisplay records on the basis of key-value pairs in MySQL
For this, use JSON_OBJECTAGG(). Let us first create a table −mysql> create table DemoTable ( Id int, FirstName varchar(100), Age int ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10, 'John', 23); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(20, 'Carol', 21); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(10, 'Sam', 24); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(20, 'Chris', 20); Query OK, 1 row affected (0.13 sec)Display all records from the ...
Read MoreMySQL query to count the number of 0s and 1s from a table column and display them in two columns?
For this, you can use the aggregate function SUM(). Let us first create a table −mysql> create table DemoTable ( isMarried tinyint(1) ); Query OK, 0 rows affected (0.84 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(0); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(0); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.19 sec) mysql> ...
Read MoreHow to use COUNT() and IF() in a single MySQL query?
Let us first create a table −mysql> create table DemoTable ( isValidUser boolean ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(false); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values(false); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected ...
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