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Database Articles
Page 370 of 547
Make all column names lower case in MySQL with a single query
Let us first create a −mysql> create table DemoTable1 -> ( -> StudentFirstName varchar(20), -> StudentLastName varchar(20), -> StudentAge int, -> StudentCountryName varchar(20) -> ); Query OK, 0 rows affected (4.20 sec)Let us now make all column names lower case in MySQL −mysql> select concat('alter table ', table_name, ' change `', column_name, '` `', -> lower(column_name), '` ', column_type, ';') -> from information_schema.columns where table_schema = 'demo';This will produce the following output −+-----------------------------------------------------------------------------------------------------------------+ | concat('alter table ', table_name, ' change `', column_name, '` `', lower(column_name), '` ', column_type, ';') | +-----------------------------------------------------------------------------------------------------------------+ | ...
Read MoreHow to select multiple max values which would be duplicate values as well in MYSQL?
For this, use the join concept. Let us first create a −mysql> create table DemoTable1389 -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentMarks int -> ); Query OK, 0 rows affected (2.73 sec)Insert some records in the table using insert command. Here, we have inserted duplicate values as well −mysql> insert into DemoTable1389(StudentMarks) values(40); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable1389(StudentMarks) values(40); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1389(StudentMarks) values(68); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable1389(StudentMarks) values(78); Query OK, ...
Read MoreDisplay the contents of a VIEW in MySQL?
Following is the syntax −select * from yourViewName;Let us first create a table −mysql> create table DemoTable1388 -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(40) -> ); Query OK, 0 rows affected (0.71 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1388(StudentName) values('Chris'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable1388(StudentName) values('Bob'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1388(StudentName) values('David'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1388(StudentName) values('Mike'); Query OK, 1 row affected (0.29 sec)Display all ...
Read MoreHow to obtain multiple rows in a single MySQL query?
To obtain multiple rows in a single MySQL query, use LIKE operator. Let us first create a table −mysql> create table DemoTable1385 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.90 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1385(Name) values('Chris Brown'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1385(Name) values('Adam Smith'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable1385(Name) values('Carol Taylor'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1385(Name) values('John ...
Read MoreInsert multiple rows in a single MySQL query
Let us first create a table −mysql> create table DemoTable1384 -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20), -> StudentAge int -> ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command. Here, we are inserting multiple rows in a single query −mysql> insert into DemoTable1384(StudentName, StudentAge) values('Chris Brown', 21), ('David Miller', 22), -> ('Carol Taylor', 19), ('Adam Smith', 23); Query OK, 4 rows affected (0.11 sec) Records: 4 Duplicates: 0 Warnings: 0Display all records from the table using select statement −mysql> select * ...
Read MoreMySQL query to find the top two highest scores
For this, use aggregate function MAX(). Let us first create a table −mysql> create table DemoTable1383 -> ( -> Id int, -> PlayerScore int -> ); Query OK, 0 rows affected (0.90 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1383 values(200, 78); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1383 values(200, 89); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1383 values(200, 89); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1383 values(200, 87); Query OK, 1 row affected (0.29 sec) mysql> insert into ...
Read MoreHow to update a MySQL table by swapping two column values?
To swap two values in a column, use CASE WHEN statement. Let us first create a table −mysql> create table DemoTable1382 -> ( -> StudentName varchar(20) -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1382 values('John'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1382 values('Chris'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1382 values('Adam'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1382 values('Bob'); Query OK, 1 row affected (0.17 sec)Display all records from the table using ...
Read MoreHow to get the maximum value from a column with alphanumeric strings beginning with specific characters in MYSQL?
For maximum value, use MAX() along with CAST() for conversion. Since we want maximum value from string-numbers beginning with specific characters, use RLIKE. Let us first create a table −mysql> create table DemoTable1381 -> ( -> DepartmentId varchar(40) -> ); Query OK, 0 rows affected (0.48 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1381 values('IT794'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1381 values('AT1034'); Query OK, 1 row affected (0.52 sec) mysql> insert into DemoTable1381 values('IT967'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1381 values('IT874'); Query ...
Read MoreMySQL UNION SELECT and IN clause in a single query
Let us first create a table −mysql> create table DemoTable1 -> ( -> StudentId int, -> StudentName varchar(20) -> ); Query OK, 0 rows affected (1.24 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(210, 'Adam'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select * from DemoTable1;This will produce the following output −+-----------+-------------+ | StudentId | StudentName | +-----------+-------------+ | 210 | Adam | +-----------+-------------+ 1 row in set (0.00 sec)Here is the query to create ...
Read MoreHow can I view cascades in MySQL?
To view cascades, use SHOW CREATE TABLE in MySQL. Let us first create a table −mysql> create table DemoTable1378 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EmployeeId varchar(20), -> EmployeeFirstName varchar(20), -> EmployeeLastName varchar(20), -> EmployeeCountryName varchar(40), -> EmployeeAge int, -> EmployeeSalary int, -> UNIQUE(EmployeeFirstName, EmployeeSalary), -> INDEX First_Last_NameIndex(EmployeeFirstName, EmployeeLastName) -> ); Query OK, 0 rows affected (0.93 sec)Let us now view cascades in MySQL −mysql> show create table DemoTable1378;This will produce the following output −+---------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table ...
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