General MySQL Oracle SQL Server

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What Is a READ ONLY Transaction in Oracle
What Is a READ ONLY Transaction in Oracle? A READ ONLY transaction is a transaction in which the read consistency is set at the transaction level. In a READ ONLY transaction, a logical snapshot of the database is created at the beginning of the transaction and released at the end of the transaction.... 2019-08-23, 2438🔥, 0💬

Adding a New DSN with the ODBC Driver for SQL Server
How To Add a New DSN with the ODBC Driver for SQL Server? Assuming that the ODBC driver for SQL Server has been installed as part of the Windows system, the next step of setting up ODBC connection to SQL Server is to create a new DSN (Data Source Name) with the ODBC Data Source Administrator: Go to ... 2024-08-06, 2437🔥, 0💬

Get System Date and Time in SQL Server Transact-SQL
How to get system date and time in SQL Server Transact-SQL? I want a list of functions for getting current system date and time. Here is a comparison of all functions that you can use to get the current date and time from the data base server system: Function Return type Precision ------------------... 2017-02-25, 2437🔥, 0💬

Export Several Tables Together in Oracle
How To Export Several Tables Together in Oracle? If you don't want to export the entire schema and only want to export several tables only, you can use the "expdp" command with the "TABLES" parameter as shown in the following tutorial exercise: &gt;cd \oraclexe\app\oracle\product\1 0.2.0\server\B... 2016-10-15, 2437🔥, 0💬

Revise and Rerun the Last SQL Command in Oracle
How To Revise and Re-Run the Last SQL Command in Oracle? If executed a long SQL statement, found a mistake in the statement, and you don't want enter that long statement again, you can use the input buffer commands to the correct last statement and re-run it. The following tutorial exercise gives yo... 2020-07-15, 2436🔥, 0💬

What Is the Implicit Cursor in Oracle
What Is the Implicit Cursor in Oracle? There is only one implicitly cursor in a session. The implicit cursor is the cursor automatically defined by PL/SQL for you. Whenever a SQL statement is executed, this cursor will be assigned to represent the execution of this statement. This implicit cursor is... 2018-02-01, 2436🔥, 0💬

Mixing Group Functions with Non-group Selection Fields in SQL Server
Can Group Functions Be Mixed with Non-group Selection Fields in SQL Server? If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of inva... 2016-10-25, 2436🔥, 0💬

PL/SQL Named Program Unit in Oracle
What Is a Named Program Unit in Oracle? A named program unit is a PL/SQL code block with an name. It consists of three parts: Declaration Part - Defining the program unit name, calling parameters, local variables and local procedures. Declaration part is required. Execution Part - Defining execution... 2018-11-29, 2434🔥, 0💬

Drop a Tablespace in Oracle
How To Drop a Tablespace in Oracle? If you have an existing tablespace and you don't want it anymore. You can delete a tablespace by using the DROP TABLESPACE statement as shown in the example below: SQL&gt; CREATE TABLESPACE my_space 2 DATAFILE '/temp/my_space.dbf' SIZE 10M; Tablespace created.... 2019-04-13, 2433🔥, 0💬

PL/SQL Anonymous Block in Oracle
What Is an Anonymous Block in Oracle? An anonymous block is a PL/SQL code block with no name. It consists of three parts: Declaration Part - Defining local variables and local procedures. Declaration part is optional. Execution Part - Defining execution logic with executable statements. Execution pa... 2018-11-29, 2433🔥, 0💬

Compilation Error in a Statement Batch in SQL Server
What happens to a Transact-SQL statement batch if there is a compilation error? If a Transact-SQL statement batch has multiple statements, and one of them has compilation error, none of the statements in the batch will be executed. The tutorial exercise below gives you some good examples: SELECT get... 2017-05-29, 2433🔥, 0💬

Delete an Existing Row from a Table in Oracle
How To Delete an Existing Row from a Table in Oracle? If you want to delete an existing row from a table, you can use the DELETE statement with a WHERE clause to identify that row. Here is good sample of DELETE statements: INSERT INTO fyi_links (url, id) VALUES ('http://www.myspace.com', 301); 1 row... 2020-01-04, 2432🔥, 0💬

What Is MyISAM in MySQL
What Is MyISAM in MySQL? MyISAM is a storage engine used as the default storage engine for MySQL database. MyISAM is based on the ISAM (Indexed Sequential Access Method) concept and offers fast data storage and retrieval. But it is not transaction safe.   ⇒ What Is InnoDB in MySQL ⇐ What Is ISAM in... 2017-07-03, 2432🔥, 0💬

Data Pump Export Utility in Oracle
What Is the Data Pump Export Utility in Oracle? Oracle Data Pump Export utility is a standalone programs that allows you to export data objects from Oracle database to operating system files called dump file set, which can be imported back to Oracle database only by Oracle Data Pump Import utility. ... 2016-10-15, 2432🔥, 0💬

Use "OUT" Parameters in Oracle
How To Use "OUT" Parameter Properly in Oracle? Here are the rules about OUT parameters: A formal OUT parameter acts like an un-initialized variable. It must be assigned with new values before the end of the procedure or function. An actual OUT parameter must be a variable. An actual OUT parameter wi... 2018-10-19, 2431🔥, 0💬

"ALTER LOGIN" - Changing the Password of a Login Name in SQL Server
How To Change the Password of a Login Name in SQL Server? If a developer lost the password of his or her login name, you can reset the password with the "ALTER LOGIN" statement as shown in this tutorial example: -- Login with sa ALTER LOGIN FYI_DBA WITH PASSWORD = 'fyicenter'; GO Command(s) complete... 2016-10-20, 2431🔥, 0💬

Delete a User Account in Oracle
How To Delete a User Account in Oracle? If you want to delete a user account and its associated schema, you can log in as SYSTEM and use the DROP USER command as shown in the following example: &gt;.\bin\sqlplus /nolog SQL&gt; connect SYSTEM/fyicenter Connected. SQL&gt; DROP USER DEV CAS... 2019-07-09, 2430🔥, 0💬

Getting Started with Transact-SQL Statements in SQL Server
Where to find answers to frequently asked questions on Getting Started with Transact-SQL Statements in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Getting Started with Transact-SQL Statements in SQL Server. Clear examples are provi... 2016-12-02, 2430🔥, 0💬

Rename an Index in Oracle
How To Rename an Index in Oracle? Let's say you have an existing index, and you don't like its name anymore for some reason, you can rename it with the ALTER INDEX ... RENAME TO statement. Here is an example script on how to rename an index: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name... 2019-05-01, 2429🔥, 0💬

String Type Conversion During Concatenation in SQL Server
What Happens When Unicode Strings Concatenate with Non-Unicode Strings in SQL Server Transact-SQL? If a Unicode string NVARCHAR is concatenated with a non-Unicode string VARCHAR, SQL Server will implicitly convert the non-Unicode string to Unicode string for concatenation. DECLARE @regcode VARCHAR(4... 2017-03-11, 2427🔥, 0💬

Use Multiple Columns in GROUP BY in Oracle
Can Multiple Columns Be Used in GROUP BY in Oracle? You can use multiple columns in the GROUP BY clause as shown in the following example. It returns how many employees are having the same salary in each department: SQL&gt; SELECT department_id, salary, count(*) 2 FROM employees GROUP BY departm... 2019-10-27, 2426🔥, 0💬

Cannot Use DDL Statements in PL/SQL in Oracle
Can DDL Statements Be Used in PL/SQL in Oracle? No, you can not run any DDL statements is PL/SQL directly. If you try to use the DROP TABLE statement inside PL/SQL, you will get a compilation error as shown below: (Connect to XE with SQL*Plus) BEGIN DROP TABLE student; -- compilation error END; /   ... 2018-10-13, 2426🔥, 0💬

What Is a Cursor Variable in Oracle
What Is a Cursor Variable in Oracle? A cursor variable is a variable of a specific REF CURSOR data type, which is a pointer to a data structure resource connects to query statement result, similar to the CURSOR data type.. The advantage of using cursor variables is that cursor variables can be used ... 2018-04-07, 2424🔥, 0💬

What Is a Data Lock in Oracle
What Is a Data Lock in Oracle? A data lock is logical flag the Oracle server is placed on data objects to give an exclusive right to a transaction. Statements in other transactions needs to respect data locks based on certain rules. Rules on data locks are: SELECT query statements do not create any ... 2019-08-19, 2423🔥, 0💬

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General MySQL Oracle SQL Server