1. Trainer: Bach Ngoc Toan– TEDU Website: http://tedu.com.vn
Lesson 42
Sql functions
Trainer: Bach Ngoc Toan– TEDU
Website:

2. SQL Server Functions SQL Server has many built-in functions.
This reference contains the string, numeric, date, conversion, and advanced functions in SQL Server.

3. Comparing with store procedure
Store procedure (SP)
Function (UDF – User defined function)
SP can return zero , single or multiple values.
Function must return a single value (which may be a scalar or a table)
We can use transaction in SP.
We can't use transaction in UDF.
SP can have input/output parameter
Only input parameter.
We can call function from SP.
We can't call SP from function.
We can't use SP in SELECT/ We can't use SP in SELECT/
We can use UDF in SELECT/ WHERE/
HAVING statement
We can use exception handling using Try-Catch block in SP.
We can't use Try-Catch block in UDF

4. Type of functions SQL Server String Functions
SQL Server Numeric Functions
SQL Server Date Functions
SQL Server Conversion Functions
SQL Server Advanced Functions
Custom functions

5. SQL Server String Functions
Description
CONCAT
Concatenates two or more strings together
LEN
Returns the length of the specified string
LTRIM
Removes leading spaces from a string
RTRIM
Removes trailing spaces from a string
SUBSTRING
Extracts a substring from a string

6. SQL Server Numeric Functions
Description
MAX
Returns the maximum value of an expression
MIN
Returns the minimum value of an expression
SUM
Returns the summed value of an expression
CEILING
Returns the smallest integer value that is greater than or equal to a number
AVG
Returns the average value of an expression
ABS
Returns the absolute value of a number

7. SQL Server Date Functions
Review lesson: Working with date

8. SQL Server Conversion Functions
Description
CAST
Converts an expression from one data type to another
CONVERT

9. SQL Server Advanced Functions
Description
ISDATE
Returns 1 if the expression is a valid date, otherwise 0
ISNULL
Lets you return an alternative value when an expression is NULL
ISNUMERIC
Returns 1 if the expression is a valid number, otherwise 0
NULLIF
Compares two expressions
COALESCE
Returns the first non-null expression in a list

10. User-defined functions
Create function
Execute function