General MySQL Oracle SQL Server

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Date and Time Literals in Oracle
How To Write Date and Time Literals in Oracle? Date and time literals can coded as shown in the following samples: SELECT DATE '2002-10-03' FROM DUAL -- ANSI date format 03-OCT-02 SELECT TIMESTAMP '1997-01-31 09:26:50.124' FROM DUAL 31-JAN-97 09.26.50.124000000 AM -- This is ANSI format   ⇒ Date and... 2020-04-14, 2339🔥, 0💬

in Oracle
How To Delete All Rows from a Table in Oracle? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise shows you a good exa... 2020-01-04, 2339🔥, 0💬

Use NULL as Conditions in Oracle
How To Use NULL as Conditions in Oracle? If you want to compare values against NULL as conditions, you should use the "IS NULL" or "IS NOT NULL" operator. Do not use "=" or "&lt;&gt;" against NULL. The sample script below shows you some good examples: SELECT 'A' IS NULL FROM DUAL; -- Error: ... 2019-12-02, 2339🔥, 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, 2339🔥, 0💬

Location of Database Files in SQL Server
Where is my database stored on the hard disk in SQL Server? If a database is created with simple CREATE DATABASE statement, the server will create two database files on the hard disk to store data and configuration information about that data bases: database_name.mdf - SQL Server Database Primary Da... 2016-11-24, 2338🔥, 0💬

What Is a User Account in Oracle
What Is a User Account in Oracle? A user account is identified by a user name and defines the user's attributes, including the following: Password for database authentication Privileges and roles Default tablespace for database objects Default temporary tablespace for query processing work space   ⇒... 2020-07-07, 2337🔥, 0💬

Define Default Values for Formal Parameters in Oracle
How To Define Default Values for Formal Parameters in Oracle? If you have an IN parameter, you can make it as an optional parameter for the calling statement by defining the formal parameter with the DEFAULT clause. This gives you the freedom of not providing the actual parameter when calling this p... 2018-10-19, 2337🔥, 0💬

Call a Sub Procedure in Oracle
How To Call a Sub Procedure in Oracle? To call a sub procedure, just use the sub procedure name as a statement. Here is another example of calling a sub procedure: SQL&gt; CREATE OR REPLACE PROCEDURE WELCOME AS 2 PROCEDURE WELCOME_PRINT(S CHAR) AS 3 BEGIN 4 DBMS_OUTPUT.PUT_LINE('Welcome to ' || ... 2018-10-26, 2336🔥, 0💬

What Is View in MySQL
What Is View in MySQL? A view is a logical table defined by a query statement.   ⇒ What Is Join in MySQL ⇐ What Is Index in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2334🔥, 0💬

Example of Passing Parameters to Procedures in Oracle
How To Pass Parameters to Procedures in Oracle? Store procedures or functions can take parameters. You need to define parameters while defining the procedure, and providing values to parameters while calling the procedure. The script below shows you how to do this: SQL&gt; CREATE OR REPLACE PROC... 2019-03-08, 2333🔥, 0💬

Parameter Modes Supported by PL/SQL in Oracle
What Are the Parameter Modes Supported by PL/SQL in Oracle? PL/SQL supports 3 parameter modes on procedure/function parameters: IN: This is the default mode. IN parameters allow the calling code to pass values into the procedure or function. OUT: OUT parameters allow the procedure or function to pas... 2018-10-19, 2333🔥, 0💬

What Are NULL Values in SQL Server
What Are NULL Values in SQL Server Transact-SQL? A NULL value is a special value that represents an unknown value. SQL Server supports NULL values with the following features: All data types used for table columns support NULL values. In another word, NULL values can be stored in database tables. In... 2017-02-05, 2333🔥, 0💬

What Is MySQL Server Daemon - mysqld in MySQL
What Is the MySQL Server Daemon - mysqld in MySQL? "mysqld" is MySQL server daemon program which runs quietly in background on your computer system. Invoking "mysqld" will start the MySQL server on your system. Terminating "mysqld" will shutdown the MySQL server. Here is a tutorial example of invoki... 2017-12-09, 2332🔥, 0💬

Turn on Error Logs in MySQL
How To Turn on Error Logs in MySQL? If you want MySQL to write critical errors into a log file, you can use the "--log-error=fileName" option at the "mysqld" command line. The tutorial exercise below shows you a good example on how to use this option: &gt;cd \mysql\bin &gt;mkdir \mysql\logs ... 2017-11-29, 2331🔥, 0💬

BETWEEN - Testing Value in a Range in SQL Server
What To Test Value Ranges with the BETWEEN Operator in SQL Server Transact-SQL? Sometimes you want to compare a value against a value range. You can do this with two regular comparison operations. But you can also use the special comparison operator BETWEEN to get it done with the following syntaxes... 2017-01-21, 2331🔥, 0💬

Insert a New Row into a Table in Oracle
How To Insert a New Row into a Table in Oracle? To insert a new row into a table, you should use the INSERT INTO statement with values specified for all columns as shown in the following example: INSERT INTO fyi_links VALUES (101, 'http://dev.fyicenter.com', NULL, 0, '30-Apr-2006'); 1 row created. S... 2020-01-29, 2330🔥, 0💬

DEFAULT - Using Column Default Values in INSERT Statements in SQL Server
How To Use Column Default Values in INSERT Statements in SQL Server? 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: INSERT INTO fyi_links... 2016-11-03, 2330🔥, 0💬

Use Values from Other Tables in UPDATE in Oracle
How To Use Values from Other Tables in UPDATE Statements in Oracle? If you want to update values in one with values from another table, you can use a subquery in the SET clause. The subquery should return only one row for each row in the update table that matches the WHERE clause. The tutorial exerc... 2020-01-21, 2329🔥, 0💬

Select Some Columns from a Table in Oracle
How To Select Some Columns from a Table in Oracle? If you want explicitly tell the query to some columns, you can specify the column names in SELECT clause. The following select statement returns only two columns from the table "departments": SQL&gt; SELECT location_id, department_name FROM DEPA... 2019-12-19, 2329🔥, 0💬

Character String Functions Supported by SQL Server 2005 in SQL Server
What Are the Character String Functions Supported by SQL Server 2005 in SQL Server Transact-SQL? SQL Server 2005 supports 23 character string functions: ASCII(char) - Returning the code value of a non-Unicode character. CHAR(int) - Returning the non-Unicode character of a code value. CHARINDEX(word,... 2017-03-07, 2329🔥, 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, 2329🔥, 0💬

Counting Groups Returned with the GROUP BY Clause in Oracle
How To Count Groups Returned with the GROUP BY Clause in Oracle? If you use the COUNT(*) function on groups returned with the GROUP BY clause, it will count the number of rows within each group, not the number of groups. If you want to count the number of groups, you can put the GROUP BY query into ... 2019-09-16, 2328🔥, 0💬

Empty Your Recycle Bin in Oracle
How To Empty Your Recycle Bin in Oracle? If your recycle bin is full, or you just want to clean your recycle bin to get rid of all the dropped tables, you can empty it by using the PURGE statement in two formats: PURGE RECYCLEBIN - Removes all dropped tables from your recycle bin. PURGE TABLE table_... 2019-05-10, 2328🔥, 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, 2327🔥, 0💬

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General MySQL Oracle SQL Server