General MySQL Oracle SQL Server

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Drop an Existing Index in Oracle
How To Drop an Existing Index in Oracle? If you don't need an existing index any more, you should delete it with the DROP INDEX statement. Here is an example SQL script: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, last_name VARCHAR(80) NOT NULL, birth_date DATE N... 2020-02-20, 3083🔥, 0💬

Show Existing Locks on the Database in Oracle
How To View Existing Locks on the Database in Oracle? As can see from the pervious tutorial exercise, performance of the second session is greatly affected by the data lock created on the database. To maintain a good performance level for all sessions, you need to monitor the number of data locks on... 2019-08-08, 3082🔥, 0💬

Create a New Table in Your Schema in Oracle
How To Create a New Table in Your Schema in Oracle? If you want to create a new table in your own schema, you can log into the server with your account, and use the CREATE TABLE statement. The following script shows you how to create a table: &gt;.\bin\sqlplus /nolog SQL&gt; connect HR/fyice... 2019-06-01, 3079🔥, 0💬

Sort Query Output in Descending Order in Oracle
How To Sort Query Output in Descending Order in Oracle? If you want to sort a column in descending order, you can specify the DESC keyword in the ORDER BY clause. The following SELECT statement first sorts the department in descending order, then sorts the salary in ascending order: SQL&gt; SELE... 2019-12-19, 3073🔥, 0💬

Oracle Tablespace - Unit of Logical Storage in Oracle
What Is an Oracle Tablespace in Oracle? An Oracle tablespace is a big unit of logical storage in an Oracle database. It is managed and used by the Oracle server to store structures data objects, like tables and indexes.   ⇒ Oracle Data File - Unit of Physical Storage in Oracle ⇐ Managing Oracle Tab... 2019-04-17, 3072🔥, 0💬

Recycle Bin - Storage to Hold Dropped Tables in Oracle
What Is Recycle Bin in Oracle? Recycle bin is a logical storage to hold the tables that have been dropped from the database, in case it was dropped in error. Tables in recycle bin can be recovered back into database by the Flashback Drop action. Oracle database recycle save the same purpose as the r... 2019-05-14, 3069🔥, 0💬

Types of Tables Supported by Oracle in Oracle
How Many Types of Tables Supported by Oracle in Oracle? Oracle supports 4 types of tables based on how data is organized in storage: Ordinary (heap-organized) table - This is the basic, general purpose type of table. Its data is stored as an unordered collection (heap) Clustered table - A clustered ... 2019-06-01, 3068🔥, 0💬

Create a New Tablespace in Oracle
How To Create a New Tablespace in Oracle? If you want a new dataspace, you can use the CREATE TABLESPACE ... DATAFILE statement as shown in the following script: SQL&gt; CREATE TABLESPACE my_space 2 DATAFILE '/temp/my_space.dbf' SIZE 10M; Tablespace created. SQL&gt; SELECT TABLESPACE_NAME, S... 2019-04-13, 3068🔥, 0💬

Use "IN" Parameters in Oracle
How To Use "IN" Parameter Properly in Oracle? Here are the rules about IN parameters: A formal IN parameter acts like constant. It can not be assigned with new values. An actual IN parameter can take a value or a variable. An actual IN parameter is passed by reference to the specified value or the v... 2018-10-19, 3068🔥, 0💬

Privilege Needed to Connect to Oracle Server in Oracle
What Privilege Is Needed for a User to Connect to Oracle Server in Oracle? Oracle deny connection to users who has no CREATE SESSION privilege. Try the following tutorial exercise, you will find out how Oracle denies connection: &gt;.\bin\sqlplus /nolog SQL&gt; connect SYSTEM/fyicenter SQL&a... 2019-07-09, 3063🔥, 0💬

Logical Operations in PL/SQL in Oracle
What Are the Logical Operations in Oracle? PL/SQL supports 3 logical operations as shown in the following sample script: PROCEDURE proc_comparison AS x BOOLEAN := TRUE; y BOOLEAN := FALSE; res BOOLEAN; BEGIN res = x AND y; res = x OR y; res = NOT x; -- more statements END;   ⇒ Categories of Data Typ... 2018-08-06, 3063🔥, 0💬

General Rules on Data Consistency in Oracle
What Are the General Rules on Data Consistency in Oracle? Here is a list of general rules on data consistency: All SQL statements always work with a snapshot of the database to provide data consistency. For READ WRITE transactions, the snapshot is taken when each statement starts. For READ ONLY tran... 2019-08-19, 3062🔥, 0💬

Drop an Existing Table 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... 2019-05-25, 3061🔥, 0💬

Working with Database Objects in Oracle PL/SQL
Where to find answers to frequently asked questions on Working with Database Objects in Oracle PL/SQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Working with Database Objects in Oracle PL/SQL. Clear answers are provided with tutorial exercis... 2018-10-13, 3060🔥, 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, 3057🔥, 0💬

Use SQL Statements in PL/SQL in Oracle
How To Use SQL Statements in PL/SQL in Oracle? SQL DML (Data Manipulation Language) statements can be included in PL/SQL code blocks directly without any changes. See the script below for examples: SQL&gt; CREATE TABLE tip (id NUMBER(5) PRIMARY KEY, 2 subject VARCHAR(80) NOT NULL, 3 description ... 2019-03-08, 3049🔥, 0💬

Relation between Database and Tablespaces in Oracle
How a Database Is Related to Tablespaces in Oracle? A database's data is collectively stored in the datafiles that constitute each tablespace of the database. For example, the simplest Oracle database would have one tablespace and one datafile. Another database can have three tablespaces, each consi... 2019-01-20, 3049🔥, 0💬

Types of Cursors Supported in PL/SQL in Oracle
How Many Types of Cursors Supported in PL/SQL in Oracle? PL/SQL supports two types of cursors: The implicit cursor - A single default cursor that automatically connects to the last DML statement executed. Explicit cursors - User defined cursors with specific DML statements and execution statuses.   ... 2018-02-01, 3049🔥, 0💬

Create an Oracle Database Manually in Oracle
How To Create an Oracle Database Manually in Oracle? Based on Oracle's Administrator Guide, there are 11 steps to create a database with the CREATE DATABASE statement: Step 1: Decide on Your Instance Identifier (SID) Step 2: Establish the Database Administrator Authentication Method Step 3: Create t... 2019-04-03, 3046🔥, 0💬

Insert a RECORD into a Table in Oracle
How To Insert a RECORD into a Table in Oracle? If you have a RECORD variable with data fields matching a table structure, you can insert a row to this table with this RECORD variable using the INSERT statement as shown in the example below: CREATE TABLE emp_temp AS SELECT * FROM employees; CREATE OR... 2018-08-14, 3046🔥, 0💬

Supported Transaction Isolation Levels in Oracle
What Are Transaction Isolation Levels Supported by Oracle in Oracle? Oracle supports two transaction isolation levels: READ COMMITTED (the default option). If the transaction contains DML that requires row locks held by another transaction, then the DML statement waits until the row locks are releas... 2019-08-19, 3045🔥, 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, 3045🔥, 0💬

Execute a Simple Stored Procedure in Oracle
How To Execute a Stored Program Unit in Oracle? If you want to execute a stored program unit, you can use the EXECUTE statement. The example script below shows how to executes a stored program unit: SQL&gt; set serveroutput on; SQL&gt; CREATE PROCEDURE Hello AS 2 BEGIN 3 DBMS_OUTPUT.PUT_LINE... 2019-03-20, 3043🔥, 0💬

Export Data with Field Delimiters in Oracle
How To Export Data with a Field Delimiter in Oracle? The previous exercise allows you to export data with fixed field lengths. If you want export data with variable field lengths and field delimiters, you can concatenate your fields with an expression in the SELECT clause as shown in the tutorial ex... 2018-06-27, 3042🔥, 0💬

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General MySQL Oracle SQL Server