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Articles on Trending Technologies
Technical articles with clear explanations and examples
How can I select rows which fall on a specific day of week in MySQL?
For specific day of week, use DAYOFWEEK().Let us first create a table −mysql> create table DemoTable785 ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerName varchar(100), ShoppingDate date ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable785(CustomerName, ShoppingDate) values('Chris', '2019-07-03'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable785(CustomerName, ShoppingDate) values('Robert', '2019-07-01'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable785(CustomerName, ShoppingDate) values('David', '2019-07-06'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable785(CustomerName, ShoppingDate) ...
Read MoreMySQL query to sort column values and ignoring quotes on one of the values
To ignore quotes while ordering column values, use ORDER BY TRIM().Let us first create a table −mysql> create table DemoTable784 ( Message varchar(100) ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command −mysql> insert into DemoTable784 values('Good'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable784 values('"This is not a Message"'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable784 values('Bye'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable784 values('Hello'); Query OK, 1 row affected (0.15 sec)Display all records from the table using ...
Read MoreCount and sort rows with a single MySQL query
Let us first create a table −mysql> create table DemoTable783 ( FirstName varchar(100) ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command −mysql> insert into DemoTable783 values('Adam'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable783 values('Chris'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable783 values('Chris'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable783 values('Adam'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable783 values('Adam'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable783 values('Robert'); Query OK, 1 ...
Read MoreMySQL query to group by column and display the sum of similar values in another column
For this, use GROUP BY HAVING clause.Let us first create a table −mysql> create table DemoTable782 ( Name varchar(100), Score int ); Query OK, 0 rows affected (1.18 sec)Insert some records in the table using insert command −mysql> insert into DemoTable782 values('John', 156); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable782 values('Carol', 250); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable782 values('Bob', 140); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable782 values('John', 126); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable782 values('John', ...
Read MoreFind the count of EMPTY or NULL columns in a MySQL table?
Let us first create a table −mysql> create table DemoTable781 ( Name varchar(100) ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command −mysql> insert into DemoTable781 values(''); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable781 values('Chris'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable781 values(''); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable781 values(null); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable781 values(null); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable781 values(''); Query OK, 1 ...
Read MoreHow to display the column names from a table excluding some in MySQL?
To exclude some of the column names, use NOT IN.Let us first create a table −mysql> create table DemoTable780 ( CustomerId int, CustomerName varchar(100), CustomerAge int, CustomerCountryName varchar(100), isMarried tinyint(1) ); Query OK, 0 rows affected (0.47 sec)Here is the query to exclude result −mysql> select group_concat(column_name) from `information_schema`.`COLUMNS` m where table_schema = 'web' and table_name = 'DemoTable780' and column_name not in ('CustomerId','CustomerCountryName') group by table_schema,table_name;This will produce the following output -+------------------------------------+ | group_concat(column_name) | +------------------------------------+ | CustomerName,CustomerAge,isMarried | +------------------------------------+ 1 row in set (0.01 sec)
Read MoreIncrement column value ‘ADD’ with MySQL SET clause
Since the column value ‘ADD’ is already a reserved word, therefore you need to use backticks around the word ADD like `ADD`.Let us see an example and create a table −mysql> create table DemoTable779 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, `ADD` int ); Query OK, 0 rows affected (0.47 sec)Insert some records in the table using insert command −mysql> insert into DemoTable779(`ADD`) values(54); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable779(`ADD`) values(89); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable779(`ADD`) values(66); Query OK, 1 row affected ...
Read MoreSelect rows from a MySQL table and display using IN()
Let us first create a table −mysql> create table DemoTable778 ( ClientId varchar(100), ClientName varchar(100) ); Query OK, 0 rows affected (1.05 sec)Insert some records in the table using insert command −mysql> insert into DemoTable778 values('J-101', 'John'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable778 values('A-102', 'Adam'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable778 values('C-103', 'Chris'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable778 values('D-104', 'David'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable778 values('R-105', 'Robert'); Query OK, 1 row affected ...
Read MoreMySQL query to display the column and its values using OR in WHERE statement
Let us first create a table −mysql> create table DemoTable777 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(100), StudentAge int ); Query OK, 0 rows affected (1.34 sec)Insert some records in the table using insert command −mysql> insert into DemoTable777(StudentName, StudentAge) values('Chris', 23); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable777(StudentName, StudentAge) values('Robert', 21); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable777(StudentName, StudentAge) values('Mike', 19); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable777(StudentName, StudentAge) values('Bob', 22); Query OK, 1 row ...
Read MoreWhy does the following error occur in MySQL: ERROR 1062 (23000): Duplicate entry?
Let’s say you have set column values as unique key and try to insert duplicate values in the table. This will lead to ERROR 1062 (23000): Duplicate entry.Let us first create a table -mysql> create table DemoTable776 ( FirstValue int, SecondValue int, unique key(FirstValue, SecondValue) ); Query OK, 0 rows affected (0.74 sec)Insert some records in the table using insert command. While inserting duplicate value, the same error arises as shown below -mysql> insert into DemoTable776 values(10, 20); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable776 values(10, 40); Query OK, 1 row affected (0.15 ...
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