Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
MySQL Articles
Page 185 of 355
How do I use the @ sign in MySQL?
To use the @ sign, use MySQL SET command. The @sign is used to set user-defined variables. Following is the syntax −SET @anyVariableName:=yourValue;Let us first create a table −mysql> create table DemoTable1331 -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1331 values(10, 'Chris'); Query OK, 1 row affected (0.71 sec) mysql> insert into DemoTable1331 values(101, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1331 values(40, 'Bob'); Query OK, 1 row affected (0.12 sec) ...
Read MoreHow to TRIM x number of characters, beginning from the last in MySQL?
For this, you can use substring() along with length(). Let us first create a table −mysql> create table DemoTable1329 -> ( -> StudentName varchar(40) -> ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1329 values('David Miller'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1329 values('Chris Brown'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1329 values('Adam Smith'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable1329 values('John Doe'); Query OK, 1 row affected (0.44 sec)Display all records from the ...
Read MoreMySQL query to extract time in a format without seconds
For this, you can use time_format(). Let us first create a table −mysql> create table DemoTable1326 -> ( -> Arrivaltime time -> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1326 values('12:10:45'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1326 values('20:00:00'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1326 values('22:45:55'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1326 values('04:10:24'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select * ...
Read MoreOrder MySQL results without identifier?
To order MySQL results without identifier, the syntax is as follows −select * from yourTableName order by 1 DESC LIMIT yourLimitValue;Let us first create a table −mysql> create table DemoTable1325 -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1325 values(100, 'Chris'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1325 values(101, 'Bob'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1325 values(120, 'David'); Query OK, 1 row affected (0.14 sec) mysql> insert ...
Read MoreHow to identify composite primary key in any MySQL database table?
You can use aggregate function count(*). If it returns a value greater than 1, that would mean the table has composite primary key.Let us first create a table −mysql> create table DemoTable1324 -> ( -> StudentId int, -> StudentName varchar(20), -> StudentAge int, -> StudentCountryName varchar(20) -> ); Query OK, 0 rows affected (0.52 sec)Here is the query to add composite primary key −mysql> alter table DemoTable1324 ADD CONSTRAINT constr_IdAgeCountry PRIMARY KEY (StudentId, StudentAge, StudentCountryName); Query OK, 0 rows affected (1.29 sec) Records: 0 Duplicates: 0 Warnings: 0Following is the query to identify composite ...
Read MoreMySQL query to get the last created table name (most recent)?
You can use the concept INFORMATION_SCHEMA.TABLES for this. Let us first create a table. This would be our most recent table −mysql> create table DemoTable1323 -> ( -> FirstName varchar(10) -> ); Query OK, 0 rows affected (0.43 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1323 values('Chris'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1323 values('David'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1323 values('Bob'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select *from DemoTable1323;This will produce ...
Read MoreCreate a MySQL table from already created table selecting specific rows?
To create a table from an already created table, use CREATE TABLE AS SELECT statement. Let us first create a table −mysql> create table DemoTable1318 -> ( -> Id int, -> FirstName varchar(10), -> LastName varchar(10), -> Age int -> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1318 values(1, 'Chris', 'Brown', 21); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1318 values(2, 'David', 'Miller', 24); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1318 values(3, 'Carol', 'Taylor', 23); Query OK, 1 row affected (0.11 ...
Read MoreHow do I return multiple results in a MySQL subquery with IN()?
In MySQL, you can easily return multiple results, but also achieve this with subquery using IN(). Let us first create a table −mysql> create table DemoTable1317 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.49 sec)Insert some records in the table using insert commandmysql> insert into DemoTable1317(Name) values('Chris Brown'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1317(Name) values('John Doe'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1317(Name) values('Adam Smith'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1317(Name) values('John Smith'); ...
Read MoreSelect words from a text already in a MySQL table
Let us first create a table −mysql> create table DemoTable1316 -> ( -> Value varchar(40) -> ); Query OK, 0 rows affected (0.47 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1316 values('MySQL'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1316 values('Java'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1316 values('MongoDB'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1316 values('C++'); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable1316;This will produce the following output. These are the ...
Read MoreMySQL query to convert empty values to NULL?
It’s easy to convert empty values to NULL using SET and WHERE. Let us first create a table −mysql> create table DemoTable1315 -> ( -> CountryName varchar(10) -> ); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command. We have set some empty values here as well −mysql> insert into DemoTable1315 values('US'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1315 values(''); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable1315 values('UK'); Query OK, 1 row affected (0.70 sec) mysql> insert into DemoTable1315 values(''); Query OK, 1 row affected (0.12 ...
Read More