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Database Articles
Page 508 of 546
Order a MySQL table by two columns?
Order a MySQL table by two columns with the help of below syntax −order by yourColumnName1 DESC, yourColumnName2 DESC;Let us first create a table for our example −mysql> create table OrderByDemo -> ( -> StudentId int, -> StudentName varchar(100), -> StudentAge int -> ); Query OK, 0 rows affected (0.57 sec)Inserting records into the table with the help of insert command. The query is as follows −mysql> insert into OrderByDemo values(1, 'John', 23); Query OK, 1 row affected (0.20 sec) mysql> insert into OrderByDemo values(3, ...
Read MoreHow to get ER model of database from server with MySQL Workbench?
To get ER model of database from server, you need to first launch MySQL Workbench. The snapshot is as follows −After that you need to select the “Database” menu −Database->Reverse EngineerAfter that a wizard will open as in the following screenshot. Add the password and press OK twice.After pressing the OK button, you will get the next wizard and you need to press next button. The following would be visible now −After that you need to select “Model” menu as I have marked in the above wizard.Model->Create Diagram from Catalog Objects After selecting the option, you will get the ER ...
Read MoreChange MySQL default character set to UTF-8 in my.cnf?
To change MySQL default character set to UTF-8 in my.cnf, firstly reach the location of my.cnf file.The following is the screenshot of “my.cnf” file. Firstly, open the C: directory and the “Program Data” folder −Now, click on “MySQL” folder −Now, click the MySQL Server 8.0 folder and open it −After opening MySQL Server 8.0, you will get “my.cnf” file location.After opening my.cnf file, you will get the character-set. Open the file and the following contens are visible −Now you can change the character-set to utf8.
Read MoreMySQL: selecting rows where a column is null?
To select rows where a column is null, you can use IS NULL from MySQL with the help of where clause.The syntax is as follows −select *from yourTableName where yourColumnName IS NULL;Let us first create a table to understand the concept −mysql> create table NULLDemo1 -> ( -> StudentId int, -> StudentName varchar(100) -> ); Query OK, 0 rows affected (1.48 sec)Inserting records into the table. The query to insert records is as follows −mysql> insert into NULLDemo1 values(NULL, 'John'); Query OK, 1 row affected (0.25 sec) mysql> ...
Read MoreWhat is the best way to display in Terminal a MySQL SELECT returning too many fields?
To achieve this, you can use the following syntax in MySQL −select *from yourTableName\G;Here, G can be used for vertical purpose. You need to add yourTableName.Let us create a table in order to understand the above syntax. Creating a table with the help of CREATE command.The following is the query to create a table −mysql> create table TooManyFieldsreturnDemo -> ( -> Id int, -> Name varchar(100), -> Age int -> ); Query OK, 0 rows affected (0.64 sec)Now you can insert records in the table ...
Read MoreHow to subtract 30 days from the current datetime in MySQL?
To subtract 30 days from current datetime, first we need to get the information about current date time, then use the now() method from MySQL. The now() gives the current date time.The method to be used for this is DATE_SUB() from MySQL. Here is the syntax to subtract 30 days from current datetime.The syntax is as follows −DATE_SUB(NOW(), INTERVAL 30 DAY);The above syntax calculates the current datetime first and in the next step, subtracts 30 days. Let us first seethe query to get the current datetime −mysql> select now();Here is the output −+---------------------+ | now() ...
Read MoreHow do I show a MySQL warning that just happened?
To show a MySQL warning, you can use the below syntax −SHOW WARNINGS;The above syntax only displays the immediate warning from MySQL prompt. Suppose you run another query between them or you have lost the MySQL connection, then SHOW WARNINGS will not work.Here is the query to display warnings −mysql> SHOW WARNINGS;Here is the output that displays immediate warning −+-------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Level | Code | Message ...
Read MoreWhich rows are returned while using LIMIT with OFFSET in MySQL?
Suppose the LIMIT is 4 and OFFSET is 6 then it will return the rows from 7 to 10 i.e. will end with row 10. The LIMIT 4 and OFFSET 6 returns row 7, 8, 9, 10.You can understand the above concept by implementing LIMIT and OFFSET. Let us create a table.mysql> create table LimitOffsettable -> ( -> Id int -> ); Query OK, 0 rows affected (0.60 sec)Let us insert some records in the table. The query is as follows −Mysql> insert into LimitOffsettable values(1); Query OK, 1 row affected ...
Read MoreMySQL create user if it does not exist?
You can create user if it does not exist with the help of “create user” command. The command will work on MySQL version 5.7.6 and above. The syntax is as follows −mysql> CREATE USER IF NOT EXISTS 'yourUserName'@'localhost' IDENTIFIED BY 'yourPassword';Apply the above syntax to create a user if it does not exist. The query is as follows −mysql> CREATE USER IF NOT EXISTS 'Smith'@'localhost' IDENTIFIED BY 'Smith123456'; Query OK, 0 rows affected (0.29 sec)To check the new user is created or not, use the below query −mysql> SELECT User FROM mysql.user;The following is the output −+------------------+ | User ...
Read MoreHow to find MySQL my.cnf on my windows computer?
To find my.cnf on Windows system, first open the command prompt with the help of shortcut key Windows + R (run). The snapshot is as follows −Type “services.msc” on command prompt and press ENTER as shown in the following screenshot −Now, a new wizard will open. The snapshot is as follows −Now, search for MySQL. The snapshot is as follows −Right click on “MySQL80” and select “Properties” as in the following screenshot −As you can see in the above screenshot, “Path to executable” tells about the location of my.cnf on Windows.
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