General MySQL Oracle SQL Server

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UPDATE Subquery Returning No Rows in SQL Server
What Happens If the UPDATE Subquery Returns No Rows in SQL Server? If you use a subquery to assign new values in the SET clause in an UPDATE statement, and the subquery returns no rows for an outer row, SQL Server will provide a NULL value to the SET clause. The tutorial exercise below shows you a g... 2016-11-02, 2145🔥, 0💬

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, 2116🔥, 0💬

Providing Column Names in INSERT Statements in SQL Server
How to provide column names in INSERT Statements in SQL Server? If you don't want to specify values for columns that have default values, or you want to specify values to columns in an order different than how they are defined, you can provide a column list in the INSERT statement. If a column is om... 2016-11-02, 2048🔥, 0💬

"LEFT OUTER JOIN ... ON" - Writing Queries with Left Outer Joins in SQL Server
How To Write a Query with a Left Outer Join in SQL Server? If you want to query from two tables with a left outer join, you can use the LEFT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a left outer join from two tables: fyi_links and fyi_rates. The join condi... 2016-10-30, 2768🔥, 0💬

"RIGHT OUTER JOIN ... ON" - Writing Queries with Right Outer Joins in SQL Server
How To Write a Query with a Right Outer Join in SQL Server? If you want to query from two tables with a right outer join, you can use the RIGHT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a right outer join from two tables: fyi_links and fyi_rates. The join c... 2016-10-30, 2764🔥, 0💬

"INNER JOIN ... ON" - Writing Queries with Inner Joins in SQL Server
How To Write a Query with an Inner Join in SQL Server? If you want to query from two tables with an inner join, you can use the INNER JOIN ... ON clause in the FROM clause. The tutorial exercise below creates another testing table and returns output with an inner join from two tables: fyi_links and ... 2016-10-30, 2696🔥, 0💬

Deleting All Rows with TRUNCATE TABLE Statement in SQL Server
How To Delete All Rows with TRUNCATE TABLE Statement in SQL Server? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise... 2016-10-30, 2248🔥, 0💬

Defining and Using Table Alias Names in SQL Server
How To Define and Use Table Alias Names in SQL Server? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names. To define an alias for a table name, just enter the alias name right after the original table name in the FROM clause as... 2016-10-30, 2183🔥, 0💬

Using SELECT Statements with Joins and Subqueries in SQL Server
Where to find answers to frequently asked questions on Using SELECT Statements with Joins and Subqueries in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Using SELECT Statements with Joins and Subqueries in SQL Server. Clear answers ... 2016-10-30, 2115🔥, 0💬

Deleting All Rows with DELETE Statements in SQL Server
How To Delete All Rows with DELETE Statements in SQL Server? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. Here is an example of deleting all rows with a DELETE statement: SELECT COUNT(*) FROM fyi_l... 2016-10-30, 2114🔥, 0💬

Deleting Multiple Rows with One DELETE Statement in SQL Server
How To Delete Multiple Rows with One DELETE Statement in SQL Server? You can delete multiple rows from a table in the same way as deleting a single row, except that the WHERE clause will match multiple rows. The tutorial exercise below deletes 3 rows from the fyi_links table: -- view rows to be dele... 2016-10-30, 2093🔥, 0💬

Joining Two Tables in a Single Query in SQL Server
How To Join Two Tables in a Single Query in SQL Server? Two tables can be joined together in a query in 4 ways: Inner Join: Returns only rows from both tables that satisfy the join condition. Left Outer Join: Returns rows from both tables that satisfy the join condition, and the rest of rows from th... 2016-10-30, 2031🔥, 0💬

Deleting an Existing Row with DELETE Statements in SQL Server
How To Delete an Existing Row with DELETE Statements in SQL Server? 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 a row for this test INSERT INTO fyi_links (url, id) V... 2016-10-30, 2018🔥, 0💬

"FULL OUTER JOIN ... ON" - Writing Queries with Full Outer Joins in SQL Server
How To Write a Query with a Full Outer Join in SQL Server? If you want to query from two tables with a full outer join, you can use the FULL OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a full outer join from two tables: fyi_links and fyi_rates. The join condi... 2016-10-29, 3079🔥, 0💬

Returning the Second 5 Rows from a Query in SQL Server
How To Return the Second 5 Rows in SQL Server? If you want to display query output in multiple pages with 5 rows per page, and the visitor wants to see the output for the second page, you need to display query output from row 6 to row 10. If you are using MySQL server, you can use the "LIMIT startRo... 2016-10-29, 2180🔥, 0💬

Using Subqueries with the EXISTS Operators in SQL Server
How To Use Subqueries with the EXISTS Operators in SQL Server? A subquery can be used with the EXISTS operator as "EXISTS (subquery)", which returns true if the subquery returns one or more rows. The following statement is a good example of "EXISTS (subquery)". It returns rows from fyi_links table t... 2016-10-29, 2147🔥, 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, 2128🔥, 0💬

Counting Groups Returned with the GROUP BY Clause in SQL Server
How To Count Groups Returned with the GROUP BY Clause in SQL Server? 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 i... 2016-10-29, 2108🔥, 0💬

"TOP" - Return the Top 5 Rows from a SELECT Query in SQL Server
How To Return the Top 5 Rows from a SELECT Query in SQL Server? If you want the query to return only the first 5 rows, you can use the "TOP 5" clause. The TOP clause takes one parameter to indicate how many top rows to return. The following statements returns the first 5 rows and 3 rows from the fyi... 2016-10-29, 2043🔥, 0💬

Writing Inner Joins with the WHERE Clause in SQL Server
How To Write an Inner Join with the WHERE Clause in SQL Server? If you don't want to use the INNER JOIN ... ON clause to write an inner join, you can put the join condition in the WHERE clause as shown in the following query example: SELECT l.id, l.url, r.comment FROM fyi_links l, fyi_rates r WHERE ... 2016-10-29, 2028🔥, 0💬

Using Subqueries with the IN Operators in SQL Server
How To Use Subqueries with the IN Operators in SQL Server? 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 ho... 2016-10-29, 2000🔥, 0💬

"AS" - Naming Query Output Columns in SQL Server
How To Name Query Output Columns in SQL Server? Each column in the query output has a default name. If you don't like the default name, you can specify a new name for any column in the query output by using the AS clause. The following statement shows you a good example: SELECT tag AS Category, YEAR... 2016-10-29, 1918🔥, 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, 1785🔥, 0💬

Selecting All Columns of All Rows from a Table in SQL Server
How To Select All Columns of All Rows from a Table with a SELECT statement in SQL Server? The simplest query statement is the one that selects all columns of all rows from a single table: "SELECT * FROM tableName". The (*) in the SELECT clause tells the query to return all columns. The missing WHERE... 2016-10-26, 4793🔥, 0💬

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General MySQL Oracle SQL Server