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Articles by Chandu yadav
Page 71 of 81
Difference between two selects in MySQL?
You can use subqueries for difference between two selects in MySQL. The syntax is as follows:SELECT *FROM yourTableName where yourColumnName NOT IN(SELECT yourColumnName FROM youTableName WHERE yourCondition;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table DifferenceSelectDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserId int, -> UserValue int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.87 sec)Insert some records in the table using insert command. The query is as follows:mysql> insert into DifferenceSelectDemo(UserId, UserValue) values(10, 10); Query ...
Read MoreCreate a procedure in MySQL with parameters?
You can create a parameter using IN and OUT. IN is used to take input parameter and OUT can be used for output.The syntax is as followsDELIMITER // CREATE PROCEDURE yourProcedureName(IN yourParameterName dataType, OUT yourParameterName dataType ) BEGIN yourStatement1; yourStatement2; . . N END; // DELIMITER ;First, we will create a table. The query to create a table is as followsmysql> create table SumOfAll -> ( -> Amount int -> ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command. The query ...
Read MoreHow to find nth highest value of a MySQL column?
To find the nth highest value of a column, you need to use ORDER BY DESC with LIMIT clause. If you want the second highest value of a column, use the below syntax:SELECT *FROM yourTableName ORDER BY DESC yourColumnName LIMIT 1, 1;If you want the fourth highest value of a column, use the below syntax:SELECT *FROM yourTableName ORDER BY DESC yourColumnName LIMIT 3, 1;If you want the first highest value of a column, use the below syntax:SELECT *FROM yourTableName ORDER BY DESC yourColumnName LIMIT 1;As discussed in the above syntax, you need to change only in LIMIT clause. To understand ...
Read MoreCheck if a string contains numbers in MySQL?
To check a string contains numbers, you can use regexp i.e. Regular Expressions. The syntax is as follows −SELECT *FROM yourTableName where yourColumnName REGEXP ‘[0-9]’;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table StringContainsNumber -> ( -> Id int not null auto_increment, -> Words text, -> primary key(Id) -> ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into StringContainsNumber(Words) values('He12345llo'); Query OK, 1 row affected (0.19 sec) ...
Read MoreHow do you OR two MySQL LIKE statements?
You can OR two like statements using the following syntax −SELECT *FROM yourTableName WHERE (yourColumnName like '%yourValue1%' OR yourColumnNamelike '%yourValue2%') AND yourColumnName = yourValue;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table ORLikeDemo -> ( -> Id int not null auto_increment, -> FirstName varchar(15), -> LastName varchar(15), -> Primary Key(Id) -> ); Query OK, 0 rows affected (1.19 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into ORLikeDemo(FirstName, LastName) values('John', 'Smith'); Query OK, ...
Read MoreSHOW TABLE statement with multiple LIKE values in MySQL?
You can use WHERE clause and OR operator to show table with multiple LIKE. The syntax is as follows:show table from yourDatabaseName where tables_in_yourDatabaseName Like ‘%anyTableName%’ or tables_in_yourDatabaseName Like ‘%anyTableName2%’ or tables_in_yourDatabaseName Like ‘%anyTableName3%’ . . . . or tables_in_yourDatabaseName Like ‘%anyTableNameN%’In the above syntax, only the table name in the database is displayed.Here the database ‘test’ and the tables in the same database is considered. The query to show tables with multiple LIKE is as follows -mysql> show tables from test -> where tables_in_test like '%userrole%' -> or tables_in_test like '%view_student%' -> or tables_in_test like '%wholewordmatchdemo%';The following is the ...
Read MoreHow can I merge two MySQL tables?
To merge two MySQL tables, use the following syntax −INSERT IGNORE INTO yourTableName1 select *from yourTableName2;We will create two tables with some records. After that the merge process will begin using the above syntax.Creating first table −mysql> create table MergeDemo1 -> ( -> id int, -> primary key(id), -> Name varchar(200) -> ); Query OK, 0 rows affected (1.00 sec)Inserting records into the table −mysql> insert into MergeDemo1 values(1, 'John'); Query OK, 1 row affected (0.21 sec)Displaying records from the tablemysql> select *from MergeDemo1;The following ...
Read MoreGrant a user permission to only view a MySQL view?
To grant a user permission to only view a MySQL view, use the below syntaxGRANT SELECT ON yourDatabaseName.yourViewName TO ' yourUserName@'yourLocalHost';First you need to display all the view names from a table. The syntax is as follows −SHOW FULL TABLES IN yourDatabaseName WHERE TABLE_TYPE LIKE 'VIEW';Now implement the above syntax to display all views from a database. Here I am using the database name ‘test’. The query is as follows −mysql> SHOW FULL TABLES IN test WHERE TABLE_TYPE LIKE 'VIEW';The following is the output −+-------------------------------+------------+ | Tables_in_test | Table_type | +-------------------------------+------------+ | empidandempname_view ...
Read MoreByte-compile Python libraries
Python is an interpreter based language. However it internally compiles the source code to byte code when a script (.py extension) is run and afterwards the bytecode version is automatically removed. When a module (apart from the precompiled built-in modules) is first imported, its compiled version is also automatically built but saved with .pyc extension in __pycache__ folder. Subsequent calls to import same module again won't recompile the module instead uses the one already built.However, a Python script file with .py extension can be compiled expilicitly without running it. The 'py_compile' module contains 'compile()' function for that purpose. Name of ...
Read MoreHow to take MySQL database backup using MySQL Workbench?
To make MySQL database backup using MySQL, first we need to install MySQL Workbench. Follow the below link to install MySQL workbench.https://dev.mysql.com/downloads/windows/installer/8.0.htmlAfter installing successfully, we need to open MySQL Workbench. Choose the option “Data Export”. Here is the snapshot.Select the database you want to export. You can also set the path here where you want to save the database.After successful completion, you can see the following screenshot.You have successfully created a backup of the above database. The following message is now visible.Export of E:\BackupDatabase has finished
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