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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to set default value for empty row in MySQL?
To set default value for empty row, use the concept of COALESCE(). Let us first create a table −mysql> create table DemoTable1863 ( FirstName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1863 values('Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1863 values(NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1863 values('David'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1863 values(NULL); Query OK, 1 row affected (0.00 sec)Display all records from the table ...
Read MoreHow to find records with a null value in a set of columns with MySQL
For this, use the concept of GREATEST(). Let us first create a table −mysql> create table DemoTable1862 ( Value1 int, Value2 int, Value3 int, Value4 int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1862 values(43, 34, 56, 42); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1862 values(NULL, 78, 65, NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1862 values(110, NULL, 78, NULL); Query OK, 1 row affected (0.00 sec)Display all ...
Read MoreHow to find rows with exact value in one or more columns with MySQL?
For this, you can use GROUP BY HAVING with subquery. Let us first create a table −mysql> create table DemoTable1861 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(20), Marks int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1861(Name, Marks) values('John', 45); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1861(Name, Marks) values('Chris', 74); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1861(Name, Marks) values('David', 89); Query OK, 1 row affected (0.00 sec) ...
Read MoreHow to use an OUT parameter / read data with SELECT from table in a MySQL procedure?
For this, you can use SELECT INTO. Let us first create a table −mysql> create table DemoTable1860 ( Amount int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1860 values(1590); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1860 values(410); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1860 values(3000); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −Mysql> select * from DemoTable1860; This will produce the following output −+--------+ | Amount ...
Read MoreIs there an easy way to rename a table in a MySQL procedure?
Yes, use the ALTER command with RENAME. Let us first create a table −mysql> create table DemoTable1859 ( Id int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1859 values(101); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1859 values(102); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1859; This will produce the following output −+------+ | Id | +------+ | 101 | | 102 | +------+ 2 rows ...
Read MoreFind duplicate column values in MySQL and display them
For this, use GROUP BY HAVING clause. Let us first create a table −mysql> create table DemoTable1858 ( ModelNumber varchar(50) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1858 values('Audi A4'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1858 values('Audi A6'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1858 values('Audi A4'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1858 values('Audi Q5'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1858 values('Audi R8'); ...
Read MoreMySQL query to get all characters before a specific character hyphen
For this, you can use SUBSTRING_INDEX(). Let us first create a table −mysql> create table DemoTable1857 ( Name varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1857 values('John-Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1857 values('Brown-Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1857 values('David-Carol-Miller'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1857; This will produce the following output −+--------------------+ | Name ...
Read MoreUsing GROUP_CONCAT() on bit fields returns garbage in MySQL? How to fix?
To fix, use group_concat() with addition of 0 with column. Let us first create a table −mysql> create table DemoTable1856 ( Id int, Value bit(1) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1856 values(101, 1); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1856 values(102, 0); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1856 values(101, 0); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1856 values(102, 1); Query OK, 1 row affected (0.00 ...
Read MoreWhich MySQL Datatype should be used for storing BloodType?
To store BloodType, use varchar(3) or ENUM. Let us first create a table −mysql> create table DemoTable1855 ( BloodType varchar(3) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1855 values('A+'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1855 values('A-'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1855 values('B+'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1855 values('B-'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1855 values('AB+'); Query OK, 1 row affected ...
Read MoreDistinct number of specific items in list with MySQL
To find distinct number of specific items, use COUNT() along with GROUP BY clause. Let us first create a table −mysql> create table DemoTable1854 ( Name varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1854 values('John-Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1854 values('Chris-Brown'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1854 values('Adam-Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1854 values('John-Doe'); Query OK, 1 row affected (0.00 sec) mysql> insert into ...
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