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Articles on Trending Technologies
Technical articles with clear explanations and examples
Select different fields in MySQL even if a field is set to null?
For this, you can use COALESCE(). Let us first create a table −mysql> create table DemoTable1336 -> ( -> FirstName varchar(20) -> , -> SecondName varchar(20) -> ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1336 values('John', NULL); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1336 values(NULL, 'Chris'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1336 values('David', 'Mike'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select * from DemoTable1336;This ...
Read MoreSelect entries with timestamp after X time in MySQL
Let us first create a table −mysql> create table DemoTable1335 -> ( -> ArrivalTime datetime -> ); Query OK, 0 rows affected (0.49 sec)Insert some records in the table using insert command. We have inserted date time records here −mysql> insert into DemoTable1335 values('2019-09-19 22:54:00'); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable1335 values('2019-09-19 22:59:00'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1335 values('2019-09-19 22:56:00'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1335 values('2019-09-19 22:52:00'); Query OK, 1 row affected (0.11 sec)Display all records from the table using ...
Read MoreInsert values in two tables with a single stored procedure call in MySQL
Following is the syntax to insert values in two tables with a stored procedure −DELIMITER // CREATE PROCEDURE yourProcedureName(anyVariableName int) BEGIN insert into yourTableName1(yourColumnName1) values(yourVariableName); insert into yourTableName2(yourColumnName2) values(yourVariableName); END //Let us first create a table −mysql> create table DemoTable1 -> ( -> StudentScore int -> ); Query OK, 0 rows affected (0.58 sec)Following is the second table −mysql> create table DemoTable2 -> ( -> PlayerScore int -> ); Query OK, 0 rows affected (0.52 sec)Here is the query to create a stored procedure and insert values in two tables ...
Read MoreMySQL row declarations for ZF?
The ZF stands for ZEROFILL i.e. row declarations for zero fill Let us first create a table. Here, we have set the int field size to be 10 −mysql> create table DemoTable1332 -> ( -> Number int(10) ZEROFILL NOT NULL DEFAULT 0 -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1332 values(); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1332 values(1); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1332 values(10); Query OK, 1 row affected (0.10 sec) mysql> insert ...
Read MoreHow 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 ...
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