General MySQL Oracle SQL Server

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Show the Current Transaction Mode in MySQL
How To Find Out the Current Transaction Mode in MySQL? If you are not sure about your current transaction mode, you can use the "SELECT @@AUTOCOMMIT FROM DUAL" statement to find out as shown in the following tutorial exercise: &gt;\mysql\bin\mysql -u dev -piyf fyi mysql&gt; SELECT @@AUTOCOMM... 2016-10-17, 2203🔥, 0💬

Viewing Log File with "mysqlbinlog" in MySQL
How To Use mysqlbinlog to View Binary Logs in MySQL? If you have binary logs turned on, you can use "mysqlbinlog" to view the binary log files. The tutorial exercise below shows you how to view two binary files together: &gt;cd \mysql\bin &gt;mysql -u root -pretneciyf test &gt;mysqlbinlo... 2017-11-29, 2202🔥, 0💬

Count Number of Rows with SELECT Statements in MySQL
How To Use SELECT Statement to Count Number of Rows in MySQL? If you want to count the number of rows, you can use the COUNT(*) function in the SELECT clause. The following tutorial exercise shows you some good example: mysql&gt; SELECT COUNT(*) FROM fyi_links; +----------+ | COUNT(*) | +-------... 2018-01-06, 2201🔥, 0💬

What Is Foreign Key in MySQL
What Is Foreign Key in MySQL? A foreign key is a single column or multiple columns defined to have values that can be mapped to a primary key in another table.   ⇒ What Is Index in MySQL ⇐ What Is Primary key in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2201🔥, 0💬

USER() - Login Name of Current User
How to obtain the login name of the current user using the USER() function? USER() is a MySQL built-in function that returns the login name of the current user. Login name is defined as the combination of user name and the client IP address where you logged in from. For example: SELECT USER(); -- +-... 2025-01-07, 2200🔥, 0💬

Drop an Existing View in MySQL
How To Drop an Existing View in MySQL? If you have an existing view, and you don't want it anymore, you can delete it by using the "DROP VIEW viewName" statement as shown in the following script: mysql&gt; DROP VIEW faqComment; Query OK, 0 rows affected (0.00 sec) mysql&gt; SELECT * FROM faq... 2018-01-24, 2200🔥, 0💬

What Is Binary Log File in MySQL
What Is Binary Log File in MySQL? MySQL server binary log file plays an important role in restoring database changes to the server. Main features on binary log files are: Binary logs can be turned on by "--log-bin=fileBaseName" option on "mysqld". Binary logs only records statements that are changin... 2017-11-29, 2197🔥, 0💬

Ways to Start MySQL Server in MySQL
How To Start MySQL Server Daemon mysqld in MySQL? There are a number of ways to start MySQL server daemon, mysqld: Double click on the file name, mysqld.exe, in a file explorer window. This is an easy way to start the server. But you will not be able to specify any command line options. Enter "mysql... 2017-12-04, 2196🔥, 0💬

Retrieving Execution Error Message in MySQL
How To Get MySQL Statement Execution Errors in MySQL? When you execute a MySQL statement with mysql_query(), and the statement failed, mysql_query() will return the Boolean value FALSE. This is good enough to tell that there is something wrong with that statement. But if you want to know more about ... 2017-10-23, 2193🔥, 0💬

ICU_VERSION() - ICU (International Components for Unicode) Version
How to obtain the version number of the ICU (International Components for Unicode) library using the ICU_VERSION() function? ICU_VERSION() is a MySQL built-in function that returns the version number of the ICU (International Components for Unicode) library. For example: SELECT ICU_VERSION(); -- +--... 2025-04-11, 2190🔥, 0💬

SELECT Statements with JOIN and Subqueries in MySQL
Where to find answers to frequently asked questions on SELECT Statements with JOIN and Subqueries in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SELECT Statements with JOIN and Subqueries in MySQL. Clear answers are provided with tutori... 2017-12-31, 2190🔥, 0💬

Group Functions with Non-group Selections in MySQL
Can Group Functions Be Mixed with Non-group Selection Fields in MySQL? If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of invalid S... 2017-10-16, 2189🔥, 0💬

Deleting Existing Rows in MySQL
How To Delete Existing Rows in a Table in MySQL? If you want to remove a row from a table, you can use the DELETE statement with a WHERE clause to identify the row. The following sample script deletes one row: &lt;?php include "mysql_connection.php"; $sql = "DELETE FROM fyi_links WHERE id = 1102... 2017-06-28, 2188🔥, 0💬

Execute SQL Statements in MySQL
How To Execute a SQL Statement in MySQL? You can run any types of SQL statements through the mysql_query() function. It takes the SQL statement as a string and returns different types of data depending on the SQL statement type and execution status: Returning FALSE, if the execution failed. Returnin... 2017-10-23, 2185🔥, 0💬

Number of Rows Selected or Affected in MySQL
How To Get the Number of Rows Selected or Affected by a SQL Statement in MySQL? There are two functions you can use the get the number of rows selected or affected by a SQL statement: mysql_num_rows($res) - Returns the number of rows selected in a result set object returned from SELECT statement. my... 2017-10-08, 2182🔥, 0💬

Drop an Existing Index in MySQL
How To Drop an Existing Index in MySQL? If you don't need an existing index any more, you should delete it with the "DROP INDEX indexName ON tableName" statement. Here is an example SQL script: mysql&gt; DROP INDEX tip_subject ON tip; Query OK, 0 rows affected (0.13 sec) Records: 0 Duplicates: 0... 2018-02-14, 2176🔥, 0💬

Using Subqueries with the IN Operator in MySQL
How To Use Subqueries with the IN Operator in MySQL? A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation. The following tutorial exercise shows you how to u... 2017-09-17, 2176🔥, 0💬

Counting Duplicated Values in a Column in MySQL
How To Count Duplicated Values in a Column in MySQL? If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAVING clause as shown in the following example. It ret... 2017-10-16, 2175🔥, 0💬

Concatenating Character Strings in MySQL
How To Concatenate Two Character Strings in MySQL? If you want concatenate multiple character strings into one, you need to use the CONCAT() function. Here are some good examples: SELECT CONCAT('Welcome',' to') FROM DUAL; Welcome to SELECT CONCAT('FYI','center','.com') FROM DUAL; FYIcenter.com   ⇒ E... 2018-04-07, 2173🔥, 0💬

Data Removed in MEMORY Tables in MySQL
What Happens to MEMORY Tables When MySQL Server Is Stopped in MySQL? If you have data rows stored in a table with the MEMORY storage engine, and the MySQL server has been shut down by the DBA, all data rows will be removed. But the table structure will remain in the server. The tutorial exercise bel... 2017-08-08, 2169🔥, 0💬

CREATE TABLE Statement in MySQL
How To Create a New Table in MySQL? If you want to create a new table, you can use the "CREATE TABLE" statement. The following tutorial script shows you how to create a table called "tip": mysql&gt; CREATE TABLE tip (id INTEGER PRIMARY KEY, subject VARCHAR(80) NOT NULL, description VARCHAR(256) ... 2018-03-10, 2168🔥, 0💬

Listing All User Accounts in MySQL
How To List All Existing User Accounts in MySQL? MySQL stores all existing user accounts in a table called "mysql.user". If you want see all user accounts, you can use the "SELECT" command as shown in the tutorial exercise below: &gt;cd \mysql\bin &gt;mysql -u root -pretneciyf mysql mysql&am... 2017-12-13, 2168🔥, 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, 2167🔥, 0💬

Data File of BDB Storage Engine in MySQL
Where Table Data Is Stored by the BDB Storage Engine in MySQL? By default, MySQL provides \mysql\data directory for all storage engines to store table data. Under \mysql\data directory, the BDB storage engine will create one file for each table to store table data and index data. If a new table is c... 2017-08-13, 2165🔥, 0💬

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General MySQL Oracle SQL Server