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Using Values from Other Tables in UPDATE Statements in SQL Server
How To Use Values from Other Tables in UPDATE Statements in SQL Server? If you want to update values in one table with values from another table, you can use a subquery as an expression in the SET clause. The subquery should return only one row for each row in the update table that matches the WHERE...
2016-11-02, 251👍, 0💬

Calculating the Difference between Two Dates in MySQL
How To Calculate the Difference between Two Dates in MySQL? If you have two dates, and you want to know how many days between them, you can use the DATEDIFF(date1, date2) function as shown below: SELECT DATEDIFF(DATE('1997-02-28'), DATE('1997-03-01')) FROM DUAL; -1   ⇒Introduction to Date and Time H...
2017-12-26, 249👍, 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, 247👍, 0💬

HAVING - Apply Filtering Criteria at Group Level in SQL Server
How To Apply Filtering Criteria at Group Level with The HAVING Clause in SQL Server? Let's say you have divided the query output into multiple groups with the GROUP BY clause. Now you are only interested in some of the groups, not all the groups. If you want to filter out some groups from the query,...
2016-10-25, 247👍, 0💬

"GROUP BY" - Dividing Query Output into Multiple Groups in SQL Server
How To Divide Query Output into Multiple Groups with the GROUP BY Clause in SQL Server? Sometimes, you want to divide the query output into multiple groups, and apply group functions on each individual groups. Dividing query output into multiple groups can be done with the GROUP BY clause. Here is t...
2016-10-25, 246👍, 0💬

Connect ASP Pages to Oracle Servers in Oracle
How To Connect ASP Pages to Oracle Servers in Oracle? If you are running Windows IIS Web server and serving ASP Web pages, you can get data from Oracle servers into your ASP pages through ODBC drivers. To do this, you need to install the correct Oracle ODBC driver and define a DSN on the IIS Web ser...
2016-10-15, 245👍, 0💬

Rename an Existing User Account in MySQL
How To Rename an Existing User Account Name in MySQL? If you want to change the name of an existing user account, you can use the "RENAME USER oldName TO newName" command. The tutorial exercise below shows you how to do this: &gt;cd \mysql\bin &gt;mysql -u root -pretneciyf mysql mysql&gt...
2017-12-13, 242👍, 0💬

Difference between CHAR and VARCHAR in MySQL
What Are the Differences between CHAR and VARCHAR in MySQL? CHAR and VARCHAR are both ASCII character data types by default. But they have the following major differences: CHAR stores values in fixed lengths. Values are padded with space characters to match the specified length. VARCHAR stores value...
2018-01-19, 241👍, 0💬

Counting Groups Returned from GROUP BY in MySQL
How To Count Groups Returned with the GROUP BY Clause in MySQL? If you use the COUNT(*) function on groups returned with the GROUP BY clause, it will count the number of rows within each group, not the number of groups. If you want to count the number of groups, you can put the GROUP BY query into a...
2017-12-21, 241👍, 0💬

Difference between CHAR and NCHAR in MySQL
What Are the Differences between CHAR and NCHAR in MySQL? Both CHAR and NCHAR are fixed length string data types. But they have the following differences: CHAR's full name is CHARACTER. NCHAR's full name is NATIONAL CHARACTER. By default, CHAR uses ASCII character set. So 1 character is always store...
2018-01-19, 240👍, 0💬

Running MySQL Server on a Specific Port in MySQL
How To Run MySQL Server on a Different Port in MySQL? By default, MySQL will listen at port number 3306 for any client connections. But you can change this by starting the server with "--port=portNumber" option. The tutorial exercise shows you how to start the server to listen to a different port nu...
2017-11-29, 240👍, 0💬

Ways to End the Current Transaction in MySQL
How To End the Current Transaction in MySQL? There are several ways the current transaction can be ended implicitly or explicitly: In "Autocommit On" mode, a single-statement transaction will be ended implicitly when the execution of the statement ends. Changes will be committed. Running the COMMIT ...
2016-10-17, 240👍, 0💬

Selecting Some Specific Rows from a Table in SQL Server
How To Select Some Specific Rows from a Table in SQL Server? If you don't want select all rows from a table, you can specify a WHERE clause to tell the query to return only the rows that meets the condition defined in the WHERE clause. The WHERE clause condition is a normal Boolean expression. If an...
2016-10-26, 239👍, 0💬

Incrementing a Date by 1 in MySQL
How To Increment Dates by 1 in MySQL? If you have a date, and you want to increment it by 1 day, you can use the DATE_ADD(date, INTERVAL 1 DAY) function. You can also use the date interval add operation as "date + INTERVAL 1 DAY". The tutorial exercise below gives you some good examples: SELECT DATE...
2017-12-26, 238👍, 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, 238👍, 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, 238👍, 0💬

Create Tables for ODBC Connection Testing in Oracle
How To Create Tables for ODBC Connection Testing in Oracle? If you want to follow the tutorial exercises in the sections below, you need to create a user account and a table for ODBC connection testing as shown here: SQL&gt; CONNECT system/retneciyf Connected. SQL&gt; CREATE USER fyi IDENTIF...
2016-10-15, 237👍, 0💬

What Is a Subquery in a SELECT Query Statement in SQL Server
What Is a Subquery in a SELECT Query Statement in SQL Server? A subquery is a SELECT statement used as part of the selection criteria of the main SELECT statement. The subquery specified in the WHERE clause will be evaluated repeated on each row of the selection base table. The output of the subquer...
2016-10-29, 233👍, 0💬

"mysqld" Command Line Options in MySQL
What Are the "mysqld" Command Line Options in MySQL? "mysqld" offers a big list of command line options. Here are some commonly used options: "--help" - Displays a short help message on how to use "mysqld". "--verbose --help" - Displays a long help messages on how to use "mysqld". "--console" - Spec...
2017-12-04, 232👍, 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, 231👍, 0💬

UPDATE Using Data from Other Tables in MySQL
How To Use Values from Other Tables in UPDATE Statements in MySQL? If you want to update values in one table with values from another table, you can use a subquery as an expression in the SET clause. The subquery should return only one row for each row in the update table that matches the WHERE clau...
2018-01-13, 227👍, 0💬

Updating Values in a Table in MySQL
How To Update Values in a Table in MySQL? If you want to update some values in one row or multiple rows in a table, you can use the UPDATE statement. The tutorial script below shows a good example: mysql&gt; UPDATE fyi_links SET counts = 999, notes = 'Good.' WHERE id = 101; Query OK, 1 row affec...
2018-01-13, 224👍, 0💬

Numeric Data Types in MySQL
What Are Numeric Data Types in MySQL? MySQL supports the following numeric data types: BIT(n) - An integer with n bits. BOOL same as BOOLEAN - Boolean values stored in 1 bit. TINYINT - A small integer stored in 1 byte. SMALLINT - A small integer stored in 2 bytes. MEDIUMINT - A medium integer stored...
2018-01-19, 217👍, 0💬

Updating Multiple Rows with One UPDATE Statement in SQL Server
How To Update Multiple Rows with One UPDATE Statement in SQL Server? If the WHERE clause in an UPDATE statement 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: SELE...
2016-11-02, 217👍, 0💬

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