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MySQL Articles
Page 299 of 355
MySQL appears to DROP USER but user still exists in MySQL.users table?
First check all the user and host from MySQL.user table with the help of select statement as shown belowmysql> select user, host from MySQL.user;The following is the output+------------------+-----------+ | user | host | +------------------+-----------+ | Bob | % | | Manish | % | | User2 | % | | mysql.infoschema | % | | mysql.session | % ...
Read MoreHow to work with array variable in MySQL?\\n
MySQL does not support array variables. To get the same result, use the table DUAL. Following is the syntax:SELECT yourValue1 AS ArrayValue FROM DUAL UNION ALL SELECT yourValue2 FROM DUAL UNION ALL SELECT yourValue3 FROM DUAL UNION ALL SELECT yourValue4 FROM DUAL UNION ALL . . . . . . SELECT yourValueN FROM DUAL;Let us create a sample table:mysql> SELECT 1 AS ArrayValue FROM DUAL UNION ALL SELECT 2 FROM DUAL UNION ALL SELECT 3 FROM DUAL UNION ALL SELECT 4 FROM ...
Read MoreReturn null for date_format when input is null in MySQL?
Use IF() function to return null for date_format when input is null in MySQL. The syntax is as follows −SELECT IF(yourDateColumnName, date_format(yourDateColumnName, '%d/%m/%Y'), NULL) FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table returnNullWhenInputIsNullDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ShippingDate datetime -> ); Query OK, 0 rows affected (1.21 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into returnNullWhenInputIsNullDemo(ShippingDate) values('2019-01-21'); Query OK, 1 row affected ...
Read MoreBulk change all entries for a particular field in MySQL?
Let us first create a demo table −mysql> create table BulkChangeDemo -> ( -> CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> CustomerName varchar(20), -> isEducated boolean -> ); Query OK, 0 rows affected (1.47 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into BulkChangeDemo(CustomerName, isEducated) values('Larry', true); Query OK, 1 row affected (0.09 sec) mysql> insert into BulkChangeDemo(CustomerName, isEducated) values('John', false); Query OK, 1 row affected (0.16 sec) mysql> insert into BulkChangeDemo(CustomerName, isEducated) values('Carol', false); Query OK, 1 row affected (0.25 sec) mysql> insert into BulkChangeDemo(CustomerName, ...
Read MoreHow to call a stored procedure using select statement in MySQL?
In MySQL, it is not possible to use select from procedure in FROM clause. You can use CALL command and after that the SELECT statement can be executed.Let us first create a table:mysql> create table DemoTable2 -> ( -> CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> CustomerName varchar(100), -> ShippingDateTime datetime -> ); Query OK, 0 rows affected (0.66 sec)Following is the query to create stored procedure:mysql> DELIMITER // mysql> CREATE PROCEDURE insert_information(Name varchar(100), shippingtime datetime) -> BEGIN -> -> INSERT INTO DemoTable2(CustomerName, ShippingDateTime) VALUES(Name, shippingtime); -> END -> ...
Read MoreMySQL index on column of int type?
Adding an index on column of int type is a good choice to run your query faster whenever your table has lots of records.If your table has less records then it is not a good choice to use index on column of int type.To understand the concept, let us create a table. The query to create a table is as follows −mysql> create table indexOnIntColumnDemo -> ( -> UserId int, -> UserName varchar(20), -> UserAge int, -> INDEX(UserId) -> ); Query OK, 0 rows affected (0.85 sec)Now check the description of table −mysql> desc ...
Read MoreMySQL query to retrieve records from the part of a comma-separated list?
To retrieve records from the part of a comma-separated list, you can use built in function FIND_IN_SET().Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(20), Marks varchar(200) ); Query OK, 0 rows affected (0.61 sec)Following is the query to insert some records in the table using insert command −mysql> insert into DemoTable(Name, Marks) values('Larry', '98, 34, 56, 89'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(Name, Marks) values('Chris', '67, 87, 92, 99'); Query OK, 1 row affected (0.15 sec) mysql> insert ...
Read MoreMySQL find/ replace string in fields?
To find/replace string in fields, the syntax is as follows −update yourTableName set yourColumnName =REPLACE(yourColumnName, yourOldValue, yourNewValue);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table FindReplaceDemo -> ( -> FileId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FileDirectory text -> ); Query OK, 0 rows affected (0.92 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into FindReplaceDemo(FileDirectory) values('C://User//MySQL'); Query OK, 1 row affected (0.19 sec) mysql> insert into FindReplaceDemo(FileDirectory) values('D://WebsiteImage//image1.jpg'); Query OK, ...
Read MoreDisplay IDs in a particular order with MySQL IN()?
To display IDs in a particular order i.e. the order of your choice use FIELD() method.Let us first create a table −mysql> create table DemoTable ( UserId int ); Query OK, 0 rows affected (0.64 sec)Following is the query to insert some records in the table using insert command −mysql> insert into DemoTable values(100); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(40); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(80); Query OK, 1 row affected (0.13 sec) ...
Read MoreHow to select or, shift to another database in MySQL using a JDBC API?
In general, You can change the current database in MySQL using the USE query.SyntaxUse DatabaseName;To change the current database using JDBC API you need to:Register the driver: Register the driver class using the registerDriver() method of the DriverManager class. Pass the driver class name to it, as parameter.Establish a connection: Connect ot the database using the getConnection() method of the DriverManager class. Passing URL (String), username (String), password (String) as parameters to it.Create Statement: Create a Statement object using the createStatement() method of the Connection interface.Execute the Query: Execute the query using the execute() method of the Statement interface.ExampleFollowing JDBC ...
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