General MySQL Oracle SQL Server

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What Do You Think about Oracle SQL Developer in Oracle
What Do You Think about Oracle SQL Developer in Oracle? To conclude this introductory FAQ collection, you should think about Oracle SQL Developer in comparison with other client tools like SQL*Plus and Oracle Web interface. SQL Developer is definitely better than the other tools, more functionality,... 2018-12-26, 2725🔥, 0💬

What Are Cursors in SQL Server
What Are Cursors in SQL Server Transact-SQL? A cursor is a special data type that represents a result set returned by a SELECT query statement. There are several notes about cursor you need to remember: Cursor data type can not be used to define table columns. Cursor data type is used on store proce... 2016-10-17, 2725🔥, 0💬

Define an Anonymous Block in Oracle
How To Define an Anonymous Block in Oracle? An anonymous block must have an execution part, which is a group of other PL/SQL statements enclosed in the BEGIN ... END statement. Here is a script on how to define a simple anonymous block with SQL*Plus: SQL&gt; set serveroutput on; SQL&gt; begi... 2018-10-30, 2724🔥, 0💬

Convert Character Strings to Times in Oracle
How To Convert Character Strings to Times in Oracle? You can convert dates to characters using the TO_CHAR() function as shown in the following examples: SELECT TO_CHAR(TO_DATE('04:49:49', 'HH:MI:SS'), 'DD-MON-YYYY HH24:MI:SS') FROM DUAL; -- Default date is the first day of the current month 01-MAY-... 2019-12-02, 2722🔥, 0💬

Creating Triggers for INSERT Statements Only in SQL Server
How To Create a Trigger for INSERT Only in SQL Server? The trigger, dml_message, provided in previous tutorials was defined to handle all 3 types of DML statements, INSERT, UPDATE, and DELETE. If you do not want the trigger to handle all 3 types of DML statements, you can list only 1 or 2 of the sta... 2016-10-24, 2722🔥, 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, 2720🔥, 0💬

Using Table Alias Names in MySQL
How To Define and Use Table Alias Names in MySQL? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names as shown in the following select statement: mysql&gt; SELECT l.id, l.url, r.comment FROM fyi_links l INNER JOIN fyi_rates ... 2017-12-31, 2720🔥, 0💬

Creating New Tables with SELECT Statements in MySQL
How To Create a New Table by Selecting Rows from Another Table in MySQL? 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 ... SELECT" statement. The tutorial script below gives you a good... 2018-03-04, 2719🔥, 0💬

Sorting Query Output in MySQL
How To Sort the Query Output in MySQL? If you want the returning rows to be sorted, you can specify a sorting expression in the ORDER BY clause. The simplest sort expression is column name who's values will be sorted by. The following select statement returns rows sorted by the values in the "counts... 2017-11-02, 2719🔥, 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, 2717🔥, 0💬

Database Basics and Terminologies in MySQL
Where to find answers to frequently asked questions on Database Basics and Terminologies in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Database Basics and Terminologies in MySQL to help you review your knowledge. A short answer is prov... 2017-07-21, 2717🔥, 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, 2716🔥, 0💬

What Is NULL Value in MySQL
What Are NULL Values in MySQL? NULL is a special value that represents no value. Here are basic rules about NULL values: NULL presents no value. NULL is not the same as an empty string ''. NULL is not the same as a zero value 0. NULL can be used as any data type. NULL should not be used in any compa... 2018-03-28, 2716🔥, 0💬

Testing Table for DML Statements in SQL Server
How To Create a Testing Table with Test Data in SQL Server? If you want to practice DML statements, like INSERT, UPDATE and DELETE statements, you should create a testing table. The tutorial exercise shows you a good example: CREATE TABLE fyi_links (id INTEGER PRIMARY KEY, url VARCHAR(80) NOT NULL, ... 2016-11-03, 2715🔥, 0💬

Using Subqueries with the IN Operator in MySQL
How To Use Subqueries with the IN Operator in MySQL? 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 u... 2017-09-17, 2713🔥, 0💬

Inserting Multiple Rows with One INSERT Statement in SQL Server
How To Insert Multiple Rows with One INSERT Statement in SQL Server? If you want to insert multiple rows with a single INSERT statement, you can use a subquery instead of the VALUES clause. Rows returned from the subquery will be inserted the target table. The following tutorial exercise gives you a... 2016-11-02, 2713🔥, 0💬

Create a Table for Transaction Testing in MySQL
How To Create a Table for Transaction Testing in MySQL? If you want to learn transaction management, you should create a table with the InnoDB storage engine. The default storage engine MyISAM does not support the transaction concept. The tutorial exercise below shows you a good example of creating ... 2016-10-17, 2713🔥, 0💬

Update Column Values on Multiple Rows in MySQL
How To Update Column Values on Multiple Rows in MySQL? If the WHERE clause in an UPDATE matches multiple rows, the SET clause will be applied to all matched rows. This rule allows you to update values on multiple rows in a single UPDATE statement. Here is a good example: mysql&gt; UPDATE fyi_lin... 2018-01-13, 2711🔥, 0💬

"INSERT INTO" - Inserting a New Row into a Table in SQL Server
How To Insert a New Row into a Table with "INSERT INTO" Statements in SQL Server? To insert a new row into a table, you can use the INSERT INTO statement with values specified for all columns as in the following syntax: INSERT INTO table_name VALUES (list_of_values_of_all columns) Note that the list... 2016-11-03, 2711🔥, 0💬

Moving Database Physical Files to New Locations in SQL Server
How to move database physical files in SQL Server? If you want to move database physical files to a new location, you can use the "ALTER DATABASE" statements to bring the database offline, and link it to the files at the new location. The following tutorial gives you a good example: ALTER DATABASE F... 2016-11-20, 2710🔥, 0💬

Inserting a New Row into a Table in MySQL
How To Insert a New Row into a Table in MySQL? 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: mysql&gt; INSERT INTO fyi_links VALUES (101, 'dev.fyicenter.com', NULL, 0, '2006-04-30'); Query OK, 1... 2018-01-16, 2709🔥, 0💬

Restrictions on External Table Columns in Oracle
What Are the Restrictions on External Table Columns in Oracle? When creating external table columns, you need to watch out some restrictions: "PRIMARY KEY" is not allowed. "NOT NULL" is not allowed. "DEFAULT value" is not allowed.   ⇒ What Is a Directory Object in Oracle ⇐ Load Data through Externa... 2016-11-27, 2709🔥, 0💬

Experiments of Data Locks in Oracle
How To Experiment a Data Lock in Oracle? If you want to have some experience with data locks, you can create two windows running two SQL*Plus sessions. In session 1, you can run a UPDATE statements to create a data lock. Before committing session 2, switch to session 2, and run a UPDATE statements o... 2019-08-08, 2707🔥, 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, 2707🔥, 0💬

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General MySQL Oracle SQL Server