General MySQL Oracle SQL Server

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Query with an Inner Join in MySQL
How To Write a Query with an Inner Join in MySQL? If you want to query from two tables with an inner join, you can use the INNER JOIN ... ON clause in the FROM clause. The tutorial exercise below creates another testing table and returns output with an inner join from two tables: fyi_links and fyi.r... 2017-12-31, 1433🔥, 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, 1433🔥, 0💬

Determining Data Types of View Columns in SQL Server
How Column Data Types Are Determined in a View in SQL Server? When you define a view, its columns are defined through a list of expressions in the underlying SELECT statement. Their data types will be determined implicitly by the expressions. For example, if the column expression is a column name of... 2016-11-03, 1433🔥, 0💬

What Is a Dead Lock in Oracle
What Is a Dead Lock in Oracle? 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 (bl... 2019-08-08, 1432🔥, 0💬

Performing Comparison on Floating Point Numbers in SQL Server
How To Perform Comparison on Floating Point Numbers in SQL Server Transact-SQL? Comparison operations on approximate (floating point) numbers are also easy to understand. Just watch out rounding operations performed during conversions. Here are two examples of floating point number comparisons: -- R... 2017-01-21, 1432🔥, 0💬

What Are Cursors in SQL Server
What Are Cursors in SQL Server Transact-SQL? A cursor is a special data type that represents a result set returned by a SELECT query statement. There are several notes about cursor you need to remember: Cursor data type can not be used to define table columns. Cursor data type is used on store proce... 2016-10-17, 1431🔥, 0💬

Declaring and Using Cursor Variables in SQL Server
How To Declare and Use Cursor Variables in SQL Server Transact-SQL? There are two ways to representing a cursor: 1. A cursor name - A static name representing a cursor object. A cursor name should be linked to a cursor object in the DECLARE statement. 2. A cursor variable name - A variable name poin... 2016-10-17, 1431🔥, 0💬

Create an Index for a Given Table in MySQL
How To Create an Index for a Given Table in MySQL? If you have a table with a lots of rows, and you know that one of the columns will be used often as a search criteria, you can add an index for that column to improve the search performance. To add an index, you can use the "CREATE INDEX" statement ... 2018-02-14, 1430🔥, 0💬

Entering Date and Time Values in SQL Server
How To Enter Date and Time values in SQL Server Transact-SQL? Transact-SQL does not support date and time literals. If you want to enter date and time values, you have to use character string literals and rely implicit casting rules to convert them into date and time values. When casting character s... 2017-04-15, 1430🔥, 0💬

Show Installed Oracle ODBC Drivers in Oracle
How To Find Out What Oracle ODBC Drivers Are Installed in Oracle? To find out what Oracle ODBC drivers are installed on your Windows system, you can use the ODBC manager to look at them: Go to Control Panel. Go to Administrative Tools. Run Data Sources (ODBC). Go to System DSN tab. Click the Add but... 2016-10-15, 1430🔥, 0💬

Scope of Local Variables in Oracle
What Is the Scope of a Local Variable in Oracle? The scope of a variable can be described with these rules: A variable is valid within the procedure or function where it is defined. A variable is also valid inside a sub procedure or function defined. If a variable name is collided with another varia... 2018-10-13, 1429🔥, 0💬

Using IN Conditions in MySQL
How To Use IN Conditions in MySQL? An IN condition is single value again a list of values. It returns TRUE, if the specified value is in the list. Otherwise, it returns FALSE. Some examples are given in the tutorial exercise below: SELECT 3 IN (1,2,3,4,5) FROM DUAL; 1 SELECT 3 NOT IN (1,2,3,4,5) FRO... 2018-03-28, 1428🔥, 0💬

Server Daemon mysqld Administration in MySQL
Where to find answers to frequently asked questions on Server Daemon mysqld Administration in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Server Daemon mysqld Administration in MySQL. Clear answers are provided with tutorial exercises o... 2017-12-09, 1428🔥, 0💬

What Is "mysqlshow" Command in MySQL
What Is "mysqlshow" in MySQL? "mysqlshow" is a command-line interface for end users to see information on tables and columns. Here are some sample commands supported by "mysqlshow": "mysqlshow" - Shows all the databases. "mysqlshow databaseName" - Shows all the tables in the specified database. "mys... 2018-02-28, 1426🔥, 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, 1426🔥, 0💬

Inner Join with the WHERE Clause in MySQL
How To Write an Inner Join with the WHERE Clause in MySQL? If you don't want to use the INNER JOIN ... ON clause to write an inner join, you can put the join condition in the WHERE clause as shown in the following query example: mysql&gt; SELECT l.id, l.url, r.comment FROM fyi_links l, fyi_rates... 2017-09-28, 1426🔥, 0💬

Show All Background Sessions in the Database in Oracle
How To Get a List of All Background Sessions in the Database in Oracle? If you don't like to use a SELECT statement to get a list of all background sessions in the current database, you can use the Reports view to do this as shown in the following tutorial example. You need to connect to the server ... 2019-01-26, 1425🔥, 0💬

Using Group Functions in the SELECT Clause in MySQL
How To Use Group Functions in the SELECT Clause in MySQL? If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query. The following select statement returns 3 values cal... 2018-01-06, 1425🔥, 0💬

Importance of Column Order in the SET Clause in Update Statements in SQL Server
Is the Order of Columns in the SET Clause Important in SQL Server? The answer is NO. The order of columns in the SET clause of the UPDATE statement is NOT important. You probably already noticed from the previous tutorial. There is a BIG DIFFERENCE among SQL Server, MySQL and Oracle on update multip... 2016-11-02, 1425🔥, 0💬

Enter a New Row Interactively in Oracle
How To Enter a New Row into a Table Interactively in Oracle? If you don't like to use the INSERT statement to enter a new row into a table, you can use the object view to enter it interactively. Follow the steps below to enter new row into table TIP: Double-click on the table name TIP. Click the Dat... 2018-10-08, 1424🔥, 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, 1423🔥, 0💬

Experiment with Dead Locks in MySQL
How To Experiment Dead Locks in MySQL? If you want to have some experience with dead locks, you can create two windows running two mysql transactions in two sessions at the REPEATABLE READ transaction isolation level. Then run some UPDATE statements as shown in the tutorial exercise below: (session ... 2017-07-21, 1423🔥, 0💬

Difference Between Clustered and Non-Clustered Indexes in SQL Server
What Is the Difference Between Clustered and Non-Clustered Indexes in SQL Server? SQL Server 2005 supports two types of indexes: clustered index and non-clustered index. Here are the main differences between them: One table can only have only one clustered index. One table can only have many non-clu... 2016-11-13, 1423🔥, 0💬

Use Existing Column Values in SET Clause in Oracle
How To Use Existing Values in UPDATE Statements in Oracle? If a row matches the WHERE clause in a UPDATE statement, existing values in this row can be used in expressions to provide new values in the SET clause. Existing values are represented by columns in the expressions. The tutorial exercise bel... 2020-01-21, 1422🔥, 0💬

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General MySQL Oracle SQL Server