General MySQL Oracle SQL Server

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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, 2557🔥, 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, 2555🔥, 0💬

Define an Explicit Cursor in Oracle
How To Define an Explicit Cursor in Oracle? An explicit cursor must be defined in the declaration part of a procedure or function with the CURSOR ... IS statement as shown in the following sample script: DECLARE CURSOR c_list IS SELECT * FROM countries; CURSOR t_list IS SELECT * FROM employees WHERE... 2018-07-22, 2549🔥, 0💬

What Is a 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... 2018-01-27, 2549🔥, 0💬

Use Group Functions in ORDER BY Clause in Oracle
Can Group Functions Be Used in the ORDER BY Clause in Oracle? If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns how many employees are having the same salary in each department. The group output is so... 2019-10-27, 2547🔥, 0💬

What Are Group Functions in Oracle
What Are Group Functions in Oracle? Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on each row of the group. MAX(exp) - Returns the maximum... 2019-12-19, 2545🔥, 0💬

Use Subqueries with the IN Operator in Oracle
How To Use Subqueries with the IN Operator in Oracle? 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 ... 2019-09-27, 2542🔥, 0💬

Ways to Create an Oracle Database in Oracle
How To Create an Oracle Database in Oracle? There are two ways to create a new database: Use the Database Configuration Assistant (DBCA) to create a database interactively. Use the CREATE DATABASE statement to create a database manually.   ⇒ Create an Oracle Database Manually in Oracle ⇐ Creating N... 2019-04-09, 2542🔥, 0💬

Loop through the Implicit Cursor in Oracle
How To Loop through Data Rows in the Implicit Curosr in Oracle? You use the FOR ... IN ... LOOP statement to loop through data rows in the implicit cursor as the following syntax: FOR row IN dml_statement LOOP (statement block with row.field) END LOOP; Here "row" is a local RECORD type variable with... 2018-07-22, 2542🔥, 0💬

Create a Single Index for Multiple Columns in Oracle
How To Create a Single Index for Multiple Columns in Oracle? If you know a group of multiple columns will be always used together as search criteria, you should create a single index for that group of columns with the "ON table_name(col1, col2, ...)" clause. Here is an example of one index for two c... 2019-04-17, 2541🔥, 0💬

Count Duplicated Values in a Column in Oracle
How To Count Duplicated Values in a Column in Oracle? 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 re... 2019-11-21, 2539🔥, 0💬

Use Variables in SQL Statements in Oracle
Can Variables Be Used in SQL Statements in Oracle? Yes, you can use variables in SQL statements as part of any expressions. The tutorial script provides you some good examples: (Connect to XE with SQL*Plus) CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, last_name VA... 2018-09-24, 2538🔥, 0💬

Connect to a Remote Server in Oracle
How To Connect to a Remote Server in Oracle? If you have an Oracle server running remotely on a network, and you know all the access information needed, you can following steps to connect your Oracle SQL Developer: Start Oracle SQL Developer Right-click on Connections Select New Database Connection ... 2018-10-08, 2535🔥, 0💬

Use Group Functions in the SELECT Clause in Oracle
How To Use Group Functions in the SELECT Clause in Oracle? 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 4 values ca... 2019-11-21, 2534🔥, 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, 2532🔥, 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, 2529🔥, 0💬

Create a Table Index in Oracle
How To Create a Table Index in Oracle? If you have a table with a lots of rows, and you know that one of the columns will be used often a search criteria, you can add an index for that column to in improve the search performance. To add an index, you can use the CREATE INDEX statement as shown in th... 2019-05-01, 2528🔥, 0💬

Read Consistency in Oracle in Oracle
How Does Oracle Handle Read Consistency in Oracle? Oracle supports two options for you on how to maintain read consistency: READ WRITE (the default option), also called statement-level read consistency. READ ONLY, also called transaction-level read consistency.   ⇒ What Is a READ WRITE Transaction i... 2019-08-23, 2526🔥, 0💬

Systems Supported by Oracle SQL Developer in Oracle
What Operating Systems Are Supported by Oracle SQL Developer in Oracle? Oracle SQL Developer is available for three types of operating Systems: Windows Linux Mac OSX   ⇒ Download-Oracle-SQL-Developer in Oracle ⇐ What Is Oracle SQL Developer in Oracle ⇑ Introduction to Oracle SQL Developer ⇑⇑ Oracl... 2019-02-18, 2522🔥, 0💬

Define a Procedure inside another Procedure in Oracle
How To Define a Procedure inside Another Procedure in Oracle? Define a procedure inside another procedure is supported by PL/SQL. The following tutorial script shows you an example: SQL&gt; CREATE OR REPLACE PROCEDURE HR.DBA_WEEK AS 2 PROCEDURE DBA_TASK (day VARCHAR2) AS 3 BEGIN 4 IF day = 'MOND... 2019-02-18, 2516🔥, 0💬

Specify Default Values in INSERT Statements in Oracle
How To Specify Default Values in INSERT Statement in Oracle? 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 VALUES ... 2020-01-29, 2514🔥, 0💬

Invoke Original Export/Import Utiities in Oracle
How To Invoke Original Export/Import Utilities in Oracle? If you really want to run the original export import utilities, you can still go to "bin" directory of the Oracle server path and run the "exp" or "imp" command. The tutorial exercise below tells you how to run the export and import utilities... 2016-10-15, 2512🔥, 0💬

Apply Filtering Criteria at Group Level in Oracle
How To Apply Filtering Criteria at Group Level in Oracle? If you want to return only specific groups from the query, you can apply filtering criteria at the group level by using the HAVING clause inside the GROUP BY clause. The following script gives you a good HAVING example: SQL&gt; SELECT dep... 2019-11-21, 2509🔥, 0💬

Define a Specific RECORD Type in Oracle
How To Define a Specific RECORD Type in Oracle? If you want to define a specific RECORD type, you need to use the TYPE ... IS RECORD statement in the declaration part of any procedure or function. The following example script defines a RECORD type called STUDENT: CREATE OR REPLACE PROCEDURE HELLO AS... 2018-09-01, 2507🔥, 0💬

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General MySQL Oracle SQL Server