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Using Multiple Columns in GROUP BY in MySQL
Can Multiple Columns Be Used in GROUP BY in MySQL? If you want to break your output into smaller groups, if you specify multiple column names or expressions in the GROUP BY clause. Output in each group must satisfy a specific combination of the expressions listed in the GROUP BY clause. The more col...
2017-10-16, 3078🔥, 0💬

What Is CSV in MySQL
What Is CSV in MySQL? CSV (Comma Separated Values) is a file format used to store database table contents, where one table row is stored as one line in the file, and each data field is separated with comma.   ⇒ What Is Transaction in MySQL ⇐ What Is BDB in MySQL ⇑ Database Basics and Terminologies ...
2016-10-16, 3076🔥, 0💬

Tables Using BDB Storage Engine in MySQL
How To Create a New Table Using the BDB Storage Engine in MySQL? BDB (BerkeleyDB) storage engine was originally developed at U.C. Berkeley. It is now maintained by Sleepycat Software, Inc., which is an Oracle company now. BDB is transaction safe, and has been used in products from many companies, li...
2017-08-13, 3075🔥, 0💬

What Is a Data Lock in MySQL
What Is a Data Lock in MySQL? MySQL uses two types of data locks at two levels to provide you the transaction isolation level you need: Share Lock at Row Level (S) - A data row is locked by a transaction for reading. Exclusive Lock at Row Level (X) - A data row is locked by a transaction for updatin...
2017-04-28, 3073🔥, 0💬

JSON_VALID() - Validating JSON Value
How to verify if value is a JSON (JavaScript Object Notation) value using the JSON_VALID() function? JSON_VALID(val) is a MySQL built-in function that returns 1 if the given value is a valid JSON value. For example: SELECT JSON_VALID('hello'), JSON_VALID('"hello"'); -- +---------------------+------- ...
2023-12-17, 3068🔥, 0💬

VERSION() - Version Number of MySQL Server
How to obtain the version number of the MySQL server using the VERSION() function? VERSION() is a MySQL built-in function that returns the version number of the MySQL server. For example: SELECT VERSION(); -- +-----------+ -- | VERSION() | -- +-----------+ -- | 8.0.17 | -- +-----------+ SELECT @@ver...
2025-01-07, 3059🔥, 0💬

Select Rows with WHERE Clause in MySQL
How To Select Some Rows from a Table in MySQL? If you don't want select all rows from a table, you can specify a WHERE clause to tell the query to return only the rows that meets the condition defined in the WHERE clause. The WHERE clause condition is a normal Boolean expression. If any data from ta...
2017-11-02, 3058🔥, 0💬

Using Column Default Values in MySQL
How To Specify Default Values in INSERT Statement in MySQL? If a column is defined with a default value in a table, you can use the key word DEFAULT in the INSERT statement to take the default value for that column. The following tutorial exercise gives a good example: mysql&gt; INSERT INTO fyi_...
2018-01-16, 3057🔥, 0💬

What Is MySQL
What Is MySQL? MySQL is an open source database management system developed by MySQL AB, http://www.mysql.com.   ⇒ What Is mSQL in MySQL ⇐ Database Basics and Terminologies in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials
2017-07-21, 3049🔥, 0💬

What Is Column in MySQL
What Is Column in MySQL? A column defines one piece of data stored in all rows of the table.   ⇒ What Is Row in MySQL ⇐ What Is Table in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials
2017-07-15, 3046🔥, 0💬

Transaction Waiting for a Data Lock in MySQL
How Long a Transaction Will Wait for a Data Lock in MySQL? If you issue a UPDATE or DELETE statement on a row that has an exclusive lock owned by another session, your statement will be blocked to wait for the other session to release the lock. But the wait will be timed out after the predefined inn...
2017-04-28, 3032🔥, 0💬

What Is "mysqldump" Command in MySQL
What Is "mysqldump" in MySQL? "mysqldump" - A command-line interface for administrators or end users to export data from the server to files. Here are some sample commands supported by "mysqldump": "mysqldump databaseName tableName" - Dumps the specified table in the specified database. "mysqldump d...
2018-05-19, 3026🔥, 0💬

List Table Names with "mysqlshow" Command in MySQL
How To Show Table Names with "mysqlshow" in MySQL? If you want to show table names with "mysqlshow", you need to specify a database name. The followings tutorial exercise shows you how to get all table names that match a pattern: If you want analyze tables with "mysqlcheck", you need to use the "--a...
2018-05-19, 3019🔥, 0💬

Loading Data Files with "mysqlimport" Command in MySQL
How To Load Data Files into Tables with "mysqlimport" in MySQL? If you want to load a data file directly into a table, you need to prepare the data file as one line per data row, and use tab character as the column delimiter. The data file name should match the target table name. The following is a ...
2018-04-28, 3014🔥, 0💬

Dump a Table to a File with "mysqldump" Command in MySQL
How To Dump a Table to a File with "mysqldump" in MySQL? If you want to dump all rows in a table from the server to a file, you can use "mysqldump" with the "-f fileName" option as show in the following tutorial exercise: &gt;cd \mysql\bin &gt;mysqldump -u root -r \temp\links.txt test links ...
2018-05-19, 3011🔥, 0💬

Returning Top 5 Rows in MySQL
How To Return Top 5 Rows in MySQL? If you want the query to return only the first 5 rows, you can use the LIMIT clause, which takes one parameter as the maximum number of rows to return. The following statement returns the first 5 rows from the fyi_links: mysql&gt; SELECT id, url, counts, tag FR...
2017-12-21, 3009🔥, 0💬

Repair MyISAM Tables in MySQL
How To Check and Repair MyISAM Tables in MySQL? If you have a corrupted MyISAM table, like the one resulted from the previous tutorial exercise, you can use the "CHECK TABLE" and "REPAIR TABLE" commands to try to repair it. The following tutorial exercise gives you a good example of repairing a corr...
2017-09-01, 3007🔥, 0💬

NAME_CONST() - PS Thread ID of Given Connect
How to provide a column name for a constant in a SELECT statement using the NAME_CONST() function? NAME_CONST(con) is a MySQL built-in function that provides a column name for a constant in a SELECT statement. For example: SELECT NAME_CONST('domain', 'dba.fyicenter.com'); -- +-------------------+ --...
2025-01-07, 3003🔥, 0💬

Entering Binary Numbers in MySQL
How To Enter Binary Numbers in SQL Statements in MySQL? If you want to enter character strings or numeric values as binary numbers, you can quote binary numbers with single quotes and a prefix of (B), or just prefix binary numbers with (0b). Binary numbers will be automatically converted into charac...
2018-03-31, 3003🔥, 0💬

Starting mysqld to Support BDB Storage Engine in MySQL
How To Start mysqld to Support the BDB Storage Engine in MySQL? The default "mysqld" program does not support the BDB storage engine. If you want to use the BDB storage engine, you can start MySQL server with the "mysqld-max" program. The tutorial exercise below shows you how to start "mysqld-max" a...
2017-08-13, 3003🔥, 0💬

What Is a Dead Lock in MySQL
What Is a Dead Lock in MySQL? A dead lock is phenomenon happens between two transactions with each of them holding a lock that blocks the other transaction as shown in the following diagram: (transaction 1) (transaction 2) update row X to create lock 1 update row Y to create lock 2 update row X (blo...
2017-04-28, 3001🔥, 0💬

DDL Commands Supported in MySQL
How Many SQL DDL Commands Are Supported by "mysql" in MySQL? There are 4 SQL Data Definition Language (DDL) commands that are supported by "mysql". They are listed below with short descriptions: "CREATE dataObjectType dataObjectName" - Creates new databases, tables, views, triggers, indexes, and oth...
2018-04-21, 2999🔥, 0💬

Tables Using MyISAM Storage Engine in MySQL
How To Create a New Table Using MyISAM Storage Engine in MySQL? MyISAM storage engine is based on the ISAM (Indexed Sequential Access Method) concept, which was first developed at IBM to store and retrieve data on secondary storage systems like tapes. MyISAM storage engine offers fast data storage a...
2017-09-12, 2994🔥, 0💬

Read Consistency Support in MySQL in MySQL
How Does MySQL Handle Read Consistency in MySQL? Read consistency is a concept that describes how consistent the output will be on two subsequent read operations. A read operation is usually a stand alone SELECT statement or a SELECT subquery in a parent statement. A database server can support up t...
2017-08-03, 2991🔥, 0💬

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