General MySQL Oracle SQL Server

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UPDATE Subquery Returning Multiple Rows in SQL Server
What Happens If the UPDATE Subquery Returns Multiple Rows in SQL Server? If a subquery is used in a UPDATE statement, it must return exactly one row for each row in the update table that matches the WHERE clause. If it returns multiple rows, SQL Server will give you an error message. To test this ou... 2016-11-02, 533👍, 0💬

Testing Table for SELECT Statements in SQL Server
How To Create a Testing Table with Test Data to try with SELECT statements in SQL Server? If you want to follow the tutorial exercises presented in this collection, you need to create a testing table and insert some test data, as shown in the following sample script: CREATE TABLE fyi_links (id INTEG... 2016-10-26, 533👍, 0💬

Creating a Logon Trigger in Express Edition in SQL Server
Can You Create a Logon Trigger in SQL Server 2005 Express Edition in SQL Server? Can you create a logon trigger in SQL Server 2005 Express Edition? The answer is no. LOGON is not a supported event type in Express Edition. The script below shows you the error message when you try to create a logon tr... 2016-10-22, 533👍, 0💬

Start a New Transaction Explicitly in MySQL
How To Start a New Transaction Explicitly in MySQL? If you are confused on the implicit new transaction rules, you can always start a new transaction with the "START TRANSACTION" command to start a new transaction explicitly. "START TRANSACTION" command works in both "Autocommit On" and "Autocommit ... 2016-10-17, 533👍, 0💬

Retrieve Field Values from RECORD Variables in Oracle
How To Retrieve Values from Data Fields in RECORD Variables in Oracle? If a variable is a RECORD variable with data fields assigned values, you can retrieve those values out of its data fields by using fields names prefixed with variable name as "variable.field_name". Here is a sample script showing... 2018-09-01, 532👍, 0💬

What Is MySQL Server Daemon - mysqld in MySQL
What Is the MySQL Server Daemon - mysqld in MySQL? "mysqld" is MySQL server daemon program which runs quietly in background on your computer system. Invoking "mysqld" will start the MySQL server on your system. Terminating "mysqld" will shutdown the MySQL server. Here is a tutorial example of invoki... 2017-12-09, 532👍, 0💬

Getting Month and Weekday Names from DATATIME Values in SQL Server
How To Get Month and Weekday Names from DATETIME Values in SQL Server Transact-SQL? In DATETIME values, the month part and weekday part have names. You can use the DATENAME() function to get the month name and weekday name from a DATETIME value in the following format: DATENAME(datepart, date) retur... 2017-02-14, 532👍, 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, 532👍, 0💬

Define and Use Table Alias Names in Oracle
How To Define and Use Table Alias Names in Oracle? 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: SQL&gt; SELECT e.first_name, e.last_name, d.department_name FROM employees e ... 2019-10-27, 531👍, 0💬

Name Conflicts between Variables and Columns in Oracle
How To Resolve Name Conflicts between Variables and Columns in Oracle? The best way to resolve name conflicts is to avoid using column names for variables.   ⇒Working with Database Objects in Oracle PL/SQL ⇒⇒Oracle Database Tutorials 2018-09-24, 531👍, 0💬

Using Subqueries in the FROM Clause in SQL Server
How To Use Subqueries in the FROM Clause in SQL Server? If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. A subquery used in this way become a temporary table, and yo... 2016-10-29, 531👍, 0💬

Improving the Trigger to Handle NULL Values in SQL Server
How To Improve the Trigger to Handle NULL Values in SQL Server? When a NULL value is concatenated with a string, the result will be a null value. So if you want the trigger to properly report NULL values, you need to enhance the trigger as shown in the following tutorial example: USE FyiCenterData; ... 2016-10-24, 531👍, 0💬

Insert Multiple Rows with 1 INSERT Statement in MySQL
How To Insert Multiple Rows with One INSERT Statement in MySQL? 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 a good exa... 2018-01-16, 530👍, 0💬

NULL Values Involved in String Operations in SQL Server
What Happens If NULL Values Are Involved in String Operations in SQL Server Transact-SQL? If NULL values are involved in string operations, the result will be string NULL values. The following tutorial script shows you some good examples: SELECT 'FyiCenter'+NULL; GO ---------- NULL SELECT LEN(NULL);... 2017-02-05, 530👍, 0💬

Running SQL Server 2005 Books Online on Your Local System in SQL Server
How to run SQL Server 2005 Books Online on your local system in SQL Server? SQL Server 2005 Books Online can be accessed by a Web browser over the Internet. But you can also download it and read it on your local system. If you have downloaded and installed SQL Server 2005 Books Online package, you f... 2016-12-04, 530👍, 0💬

What Are Views in SQL Server
What Are Views in SQL Server? A view is a database object that represents the data in one or more tables in the same structure as a separate table. Here are some basic rules about views: Tables store real data. Views do not store real data. Views must have underlying tables to provide data. Each vie... 2016-11-08, 530👍, 0💬

Show Table Columns Used in an Index in Oracle
How To See the Table Columns Used in an Index in Oracle? You can a list of indexes in your schema from the USER_INDEXES view, but it will not give you the columns used in each index in the USER_INDEXES view. If you want to see the columns used in an index, you can use the USER_IND_COLUMNS view. Here... 2019-04-17, 529👍, 0💬

Create Additional Tablespaces in Oracle
How To Create Additional Tablespaces for an New Database in Oracle? This is Step 8. Creating additional tablespaces can be done by using the CREATE TABLESPACE statement as shown in the following sample script: SQL&gt; CREATE TABLESPACE users 2 DATAFILE '/oraclexe/oradata/FYI/users01 .dbf'SIZE 10... 2019-03-27, 529👍, 0💬

Expressions with NULL Values in MySQL
What Happens If NULL Values Are Involved in Expressions in MySQL? If NULL values are used in expressions, the resulting values will be NULL values. In other words: Arithmetic expressions with NULL values result NULL values. Comparison expressions with NULL values result NULL values. Logical expressi... 2018-03-28, 529👍, 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, 529👍, 0💬

Create a New View in MySQL
How To Create a New View in MySQL? You can create a new view based on one or more existing tables by using the "CREATE VIEW viewName AS selectStatement" statement as shown in the following script: mysql&gt; CREATE TABLE comment (faqID INTEGER, message VARCHAR(256)); Query OK, 0 rows affected (0.... 2018-01-24, 529👍, 0💬

Creating a New Database in MySQL
How To Create a New Database in MySQL? A database in a MySQL server is a logical container used to group tables and other data objects together as a unit. If you are the administrator of the server, you can create a new databases using the CREATE DATABASE statements with MySQL client interface progr... 2017-11-11, 529👍, 0💬

Close MySQL Connection Objects in MySQL
How To Close MySQL Connection Objects in MySQL? MySQL connection objects created with mysql_connect() calls should be closed as soon as you have finished all of your database access needs by calling mysql_close($con) function. This will reduce the consumption of connection resources on your MySQL se... 2017-11-11, 529👍, 0💬

"DROP DATABASE" - Deleting Databases in SQL Server
How to delete a database in SQL Server? If you created a database incorrectly, or you have a database that is not needed any more, you can delete it with the "DROP DATABASE" statement with this syntax: DROP DATABASE database_name For example, execute this statement: DROP DATABASE FyiCenterData GO Th... 2016-11-24, 529👍, 0💬

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General MySQL Oracle SQL Server