Skip to main content

Cast or Convert

SQL Server programmers can choose between two functions in SQL Server for converting expressions from one type to another. In many cases there will be a need within a stored procedure or other routine to convert data from, say, a datetime type to a varchar type; CONVERT and CAST are used for such things.

Because SQL Server provides both functions, there may be some confusion about which is best to use and under what circumstances. CONVERT is specific to SQL Server, and allows for a greater breadth of flexibility when converting between date and time values, fractional numbers, and monetary signifiers.

CAST is the more ANSI-standard of the two functions, meaning that while it's more portable (i.e., a function that uses CAST can be used in other database applications more or less as-is), it's also less powerful. CAST is also required when converting between decimal and numeric values to preserve the number of decimal places in the original expression. For those reasons, it's best to use CAST first, unless there is some specific thing that only CONVERT can provide

Syntax:
CAST ( xx as decimal)
CONVERT(decimal, xx )

Query: select cast(-0.00000000000000000000000000000000000000118 as real) as [cast result]
Output:
The number '0.00000000000000000000000000000000000000118' is out of the range for numeric representation (maximum precision 38).

Query: select convert(real, '-0.00000000000000000000000000000000000000118') as [convert result]
Output: 0
Labels:

Comments

Post a Comment

Popular posts from this blog

JavaScript Interview Questions

This is a compilations of all the interview questions related to Javascript that i have encountered.  Q: Difference between window.onload and onDocumentReady? A: The onload event does not fire until every last piece of the page is loaded, this includes css and images, which means there’s a huge delay before any code is executed. That isnt what we want. We just want to wait until the DOM is loaded and is able to be manipulated. onDocumentReady allows the programmer to do that. Q:  What is the difference between == and === ? A: The == checks for value equality, but === checks for both type and value. Few examples: "1" == 1; // value evaluation only, yields true "1" === 1; // value and type evaluation, yields false "1" == true; // "1" as boolean is true, value evaluation only, yields true "1" === false; // value and type evaluation, yields false Q: What does “1″+2+5 evaluate to? What about 5 + 2 +...
1 comment
Read more

Adding a linked Server using the GUI

Adding a linked Server using the GUI There are two ways to add another SQL Server as a linked server.  Using the first method, you need to specify the actual server name as the “linked server name”.  What this means is that everytime you want to reference the linked server in code, you will use the remote server’s name.  This may not be beneficial because if the linked server’s name changes, then you will have to also change all the code that references the linked server.  I like to avoid this method even though it is easier to initially setup.  The rest of the steps will guide you through setting up a linked server with a custom name: To add a linked server using SSMS (SQL Server Management Studio), open the server you want to create a link from in object explorer. In SSMS, Expand Server Objects -> Linked Servers -> (Right click on the Linked Server Folder and select “New Linked Server”) Add New Linked Server The “New Linked Server” Dialog a...
Post a Comment
Read more

Lookup!!

LOOKUP As the name suggests, Excel gives us the option to lookup for a number or text in a specific area which needs to be stated. If the value is found the corresponding value or text is returned The syntax for LOOKUP is as follows; =LOOKUP( lookup_value , lookup_vector , result_vector )       In the diagram, column D contains varying salaries, against which there is a company car in column E which corresponds to each salary. For example, a £20030 salary gets a Golf, a £35000 salary gets a Scorpio. A LOOKUP formula can be used to return whatever car is appropriate to a salary figure that is entered. In this case, the lookup_value is the cell where the salary is entered (B13), the lookup_vector is the salary column (D3:D11), and the result_vector is the car column (E3:E11). Hence the formula; =LOOKUP(B13,D3:D11,E3:E11) Typing 40000 in cell B13 will set the lookup_value. LOOKUP will search through the lookup_vector to find the matching salary, and return th...
Post a Comment
Read more