General MySQL Oracle SQL Server

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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, 2979🔥, 0💬

CREATE CLUSTERED INDEX - Adding Clustered Indexes in SQL Server
How To Create a Clustered Index in SQL Server? If there is no primary key in a table, you can add one clustered index to that table with CREATE CLUSTERED INDEX statement. The tutorial exercise below shows you how to create a clustered index: USE FyiCenterData; GO -- Drop the old table, if needed DRO... 2016-11-13, 2977🔥, 0💬

PHP ODBC - Including Date and Time Values in SQL Statements
PHP ODBC - How To Include Date and Time Values in SQL Statements? If you want to provide date and time values in a SQL statement, you should write them in the format of "yyyy-mm-dd hh:mm:ss", and quoted with single quotes ('). The tutorial exercise below shows you two INSERT statements. The first on... 2024-05-05, 2976🔥, 0💬

List All Tables with "mysql" Command in MySQL
How To Show All Tables with "mysql" in MySQL? If you want to see all the tables in a database, you run the non-SQL command "SHOW TABLES" at the "mysql" prompt. See the following tutorial exercise for example: &gt;cd \mysql\bin &gt;mysql -u root test Welcome to the MySQL monitor. Commands end... 2018-02-28, 2976🔥, 0💬

Selecting an Existing Database in MySQL
How To Select an Exiting Database in MySQL? The first thing after you have created a connection object to the MySQL server is to select the database where your tables are located, by using the mysql_select_db() function. If your MySQL server is offered by your Web hosting company, they will assign a... 2017-10-23, 2975🔥, 0💬

Create a Table Interactively in Oracle
How To Create a Table Interactively in Oracle? If you don't want to use SQL statements to create a new table, you use SQL Developer to create one interactively. Follow the steps below to create a new table called: TIP Right-click on the Tables in the object tree area. Select Create TABLE. Create Tab... 2018-10-08, 2974🔥, 0💬

Differences of CHAR and NCHAR in SQL Server Transact-SQL
What Are the Differences between CHAR and NCHAR in SQL Server Transact-SQL? Both CHAR and NCHAR are fixed length data types in Transact-SQL. But they have the following main differences: CHAR stores characters based on the code page with 1 byte per character most of the time. NCHAR stores characters... 2017-04-04, 2974🔥, 0💬

Returning the Second 5 Rows from a Query in SQL Server
How To Return the Second 5 Rows in SQL Server? If you want to display query output in multiple pages with 5 rows per page, and the visitor wants to see the output for the second page, you need to display query output from row 6 to row 10. If you are using MySQL server, you can use the "LIMIT startRo... 2016-10-29, 2974🔥, 0💬

Create a New Table by Selecting Rows from Another Table in Oracle
How To Create a New Table by Selecting Rows from Another Table in Oracle? Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the CREATE TABLE...AS SELECT statement to do this. Here is an example script: &... 2019-06-01, 2972🔥, 0💬

What Is Oracle SQL Developer in Oracle
What Is Oracle SQL Developer in Oracle? Oracle SQL Developer is a new, free graphical tool that enhances productivity and simplifies database development tasks. With SQL Developer, you can browse database objects, run SQL statements and SQL scripts, and edit and debug PL/SQL statements. You can also... 2019-02-18, 2969🔥, 0💬

Numeric Comparison Operations in Oracle
What Are the Numeric Comparison Operations in Oracle? PL/SQL supports 6 basic numeric comparison operations as shown in the following sample script: PROCEDURE proc_comparison AS res BOOLEAN; BEGIN res := 1 = 2; res := 1 &lt; 2; res := 1 &gt; 2; res := 1 &lt;= 2; res := 1 &gt;= 2; res... 2018-08-06, 2969🔥, 0💬

EXISTS - Testing Subquery Results in SQL Server
How To Test Subquery Results with the EXISTS Operator in SQL Server Transact-SQL? EXISTS is a special operator used to test subquery results. EXISTS can be used in two ways: EXISTS (SELECT ...) -- Returns TRUE if the specified subquery has one or more rows returned. NOT EXISTS (SELECT ...) -- Return... 2017-01-21, 2969🔥, 0💬

SINGLE_USER/MULTI_USER - Database User Access Options in SQL Server
How to set database to be SINGLE_USER in SQL Server? Databases in SQL Server have three user access options: MULTI_USER - All users that have the appropriate permissions to connect to the database are allowed. This is the default. SINGLE_USER - One user at a time is allowed to connect to the databas... 2016-11-20, 2969🔥, 0💬

DROP TABLE Statement in Oracle
How To Drop an Existing Table in Oracle? If you want to delete an existing table and its data rows, you can use the DROP TABLE statement as shown in this script: SQL&gt; connect HR/fyicenter Connected. SQL&gt; CREATE TABLE emp_dept_10 2 AS SELECT * FROM employees WHERE department_id=10; Tabl... 2020-02-20, 2968🔥, 0💬

PL/SQL Procedure in Oracle
What Is a Procedure in Oracle? A procedure is a named program unit. It consists of three parts: Declaration Part - Defining the procedure name, calling parameters, local variables and local procedures. Declaration part is required. Execution Part - Defining execution logic with executable statements... 2018-11-29, 2967🔥, 0💬

System Defined User Roles in Oracle
What Are the System Predefined User Roles in Oracle? Oracle 10g XE comes with 3 predefined roles: CONNECT - Enables a user to connect to the database. Grant this role to any user or application that needs database access. RESOURCE - Enables a user to create certain types of schema objects in his own... 2019-07-30, 2966🔥, 0💬

Pass a Parameter to a Cursor in Oracle
How To Pass a Parameter to a Cursor in Oracle? When you define a cursor, you can set a formal parameter in the cursor. The formal parameter will be replaced by an actual parameter in the OPEN cursor statement. Here is a good example of a cursor with two parameters: CREATE OR REPLACE PROCEDURE FYI_CE... 2018-07-18, 2966🔥, 0💬

Rollback the Current Transaction in MySQL
How To Rollback the Current Transaction in MySQL? If you have used some DML statements updated some data objects, you find a problem with those updates, and you don't want those updates to be permanently recorded in the database, you can use the ROLLBACK command. It will remove all the database chan... 2016-10-17, 2966🔥, 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, 2965🔥, 0💬

Experiment with Data Locks in MySQL
How To Experiment Data Locks in MySQL? If you want to have some experience with data locks, you can create two windows running two mysql transactions in two sessions. In session 1, you can run a UPDATE statement with REPEATABLE READ transaction isolation level to create an exclusive lock. Before com... 2017-04-28, 2965🔥, 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, 2964🔥, 0💬

What Is Primary key in MySQL
What Is Primary Key in MySQL? A primary key is a single column or multiple columns defined to have unique values that can be used as row identifications.   ⇒ What Is Foreign Key in MySQL ⇐ What Is Row in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2963🔥, 0💬

Creating Databases with Specified Physical Files in SQL Server
How to create database with physical files specified in SQL Server? If you don't like the default behavior of the CREATE DATABASE statement, you can specify the physical database files with a longer statement: CREATE DATABASE database_name ON (NAME = logical_data_name, FILENAME = physical_data_name,... 2016-11-24, 2963🔥, 0💬

JSON_TYPE() - Detecting Type of JSON Value
How to detect the type of a JSON (JavaScript Object Notation) value using the JSON_TYPE() function? JSON_TYPE(json) is a MySQL built-in function that returns the data type of a JSON (JavaScript Object Notation) value. For example: SELECT JSON_TYPE('[]'), JSON_TYPE('{}'); -- +-----------------+------... 2025-03-12, 2962🔥, 0💬

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General MySQL Oracle SQL Server