The SQL CREATE DATABASE Statement
The CREATE DATABASE statement is used to create a new SQL database.
Syntax
CREATE DATABASE databasename;
Category: SQL
SQL Operators
SQL Arithmetic Operators
| Operator | Description |
|---|---|
| + | Add |
| Subtract | |
| * | Multiply |
| / | Divide |
| % | Modulo |
SQL Comments
SQL Comments
Comments are used to explain sections of SQL statements, or to prevent execution of SQL statements.
Note: Comments are not supported in Microsoft Access databases!
Single Line Comments
Single line comments start with --.
Any text between — and the end of the line will be ignored (will not be executed).
The following example uses a single-line comment as an explanation : Continue reading SQL Comments
SQL Stored Procedures for SQL Server
What is a Stored Procedure?
A stored procedure is a prepared SQL code that you can save, so the code can be reused over and over again.
So if you have an SQL query that you write over and over again, save it as a stored procedure, and then just call it to execute it.
You can also pass parameters to a stored procedure, so that the stored procedure can act based on the parameter value(s) that is passed. Continue reading SQL Stored Procedures for SQL Server
SQL NULL Functions
SQL IFNULL(), ISNULL(), COALESCE(), and NVL() Functions
Look at the following “Products” table:
| P_Id | ProductName | UnitPrice | UnitsInStock | UnitsOnOrder |
|---|---|---|---|---|
| 1 | Jarlsberg | 10.45 | 16 | 15 |
| 2 | Mascarpone | 32.56 | 23 | |
| 3 | Gorgonzola | 15.67 | 9 | 20 |
Suppose that the “UnitsOnOrder” column is optional, and may contain NULL values. Continue reading SQL NULL Functions
SQL CASE Expression
The SQL CASE Expression
The CASE expression goes through conditions and returns a value when the first condition is met (like an if-then-else statement). So, once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause.
If there is no ELSE part and no conditions are true, it returns NULL. Continue reading SQL CASE Expression
SQL INSERT INTO SELECT Statement
The SQL INSERT INTO SELECT Statement
The INSERT INTO SELECT statement copies data from one table and inserts it into another table.
The INSERT INTO SELECT statement requires that the data types in source and target tables match.
Note: The existing records in the target table are unaffected. Continue reading SQL INSERT INTO SELECT Statement
SQL SELECT INTO Statement
The SQL SELECT INTO Statement
The SELECT INTO statement copies data from one table into a new table.
SELECT INTO Syntax
Copy all columns into a new table:
SELECT *
INTO newtable [IN externaldb]
FROM oldtable
WHERE condition;
Copy only some columns into a new table : Continue reading SQL SELECT INTO Statement
SQL ANY and ALL Operators
The SQL ANY and ALL Operators
The ANY and ALL operators allow you to perform a comparison between a single column value and a range of other values.
The SQL ANY Operator
The ANY operator:
- returns a boolean value as a result
- returns TRUE if ANY of the subquery values meet the condition
ANY means that the condition will be true if the operation is true for any of the values in the range. Continue reading SQL ANY and ALL Operators
SQL EXISTS Operator
The SQL EXISTS Operator
The EXISTS operator is used to test for the existence of any record in a subquery.
The EXISTS operator returns TRUE if the subquery returns one or more records.
EXISTS Syntax
SELECT column_name(s)
FROM table_name
WHERE EXISTS
(SELECT column_name FROM table_name WHERE condition);