Many SQL we write is explicitly written into the stored procedure. This is what we call the static SQL.
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Did you notice that there are two statements here? Each statement returns a summary of JobTitles for a specific employee birth year. If we want to add more birth years, then we need to add more statements. What if we only had to write the statement once and be able to change the year on-the-fly? Instead of having the statements typed directly into the stored procedure, the SQL statements are first built and defined in variables.
The code in these variables is then executed. The dynamic SQL is highlighted in green. This is the SQL that is built for each birthYear. As the SQL is built, it is stored in statement. The statement form is. The system stored procedures extend the language and provide more features for you to use. Let us assume that you have been asked to write a store procedure that returns either the average LineTotal or sum of LineTotal by ProductID for products shipped in Your boss would prefer to have this written as a stored procedure.
The stored procedure should accept one parameter ReturnAverage. The SQL is built and saved into the variable statement. This variable is built based on the parameter value returnAverage. If set to 1, then function represents the Average; otherwise, Summation. You can see where the SQL is then built to create statement. Notice the color coding.In some applications, having hard coded SQL statements is not appealing because of the dynamic nature of the queries being issued against the database server.
Build Dynamic SQL in a Stored Procedure
Because of this sometimes there is a need to dynamically create a SQL statement on the fly and then run that command. This can be done quite simply from the application perspective where the SQL statement is built on the fly whether you are using ASP. NET, ColdFusion or any other programming language. But how do you do this from within a SQL Server stored procedure? Here are a few options:. We will use the AdventureWorks database for the below examples. Although generating SQL code on the fly is an easy way to dynamically build statements, it does have some drawbacks.Dynamic sql output parameter
One issue is the potential for SQL Injection where malicious code is inserted into the command that is being built. The examples below are very simple to get you started, but you should be aware of SQL Injection and ways to prevent it by making sure your code is robust to check for any issues before executing the statement that is being built. Another issue is the possible performance issues by generating the code on the fly.Swift create uiimage of size
You don't really know how a user may use the code and therefore there is a potential for a query to do something you did not expect and therefore become a performance issue. So once again, you should make sure your code checks for any potential problems before just executing the generated code.
This can be done easily such as the following example shows. To learn more about stored procedure development check out this tutorial. With this approach you are building the SQL statement on the fly and can pretty much do whatever you need to in order to construct the statement.
Let's say we want to be able to pass in the column list along with the city. As you can see from this example handling the city value is not at straight forward, because you also need to define the extra quotes in order to pass a character value into the query.
These extra quotes could also be done within the statement, but either way you need to specify the extra single quotes in order for the query to be built correctly and therefore run. With this approach you have the ability to still dynamically build the query, but you are also able to use parameters as you could in example 1.
This saves the need to have to deal with the extra quotes to get the query to build correctly. In addition, using this approach you can ensure that the data values being passed into the query are the correct datatypes. So here are three different ways of writing dynamic queries.In some cases, we may want to create a query that we can use many times, but with a different value each time. By providing parameters in our SQLwe can create a single query that serves up answers to lots of different questions.
It adds flexibility to our database because the end users and we can define our questions.
Passing Dynamic Query Values from Excel to SQL Server
SQL Server allows us to answer this kind of questions with a parameter query. By adding a parameter in our SQL queryit allows us to pass additional information every time the query is viewed or run.
In the below query, if we want to get the employee data from different departments, we only need to change the value of DeptName. The first one is the SQL string that we would like to execute. The second one is the parameter that we need to supply for the query, and the third one is the actual value that we pass into the query. We may want to turn our queries into stored procedures for efficiency, especially when our SQL queries become longer and more complex.
Stored procedures in SQL Server accept parameters passed to them just like many other programming languages. To call a stored procedure with a parameter, we need to specify the parameter at the end of the EXEC statement. More simply, we can call it by passing the text Engineering directly after the stored procedure name.
One of the benefits of using parameterized queries is that it prevents SQL injection and help our application becomes secure. However, there are things that we cannot pass as parameters in our SQL queries, such as:. When we want to dynamically pass the table and column names into our SQL queries, we need to do this in a more risky way by constructing the SQL string at runtime. Building this string can make SQL injection attack easier, especially when the end users supply the table and column names.
We may need to perform string validations on every user input before executing the final query to the database to ensure our database is safe. Most of the time, the problem you will need to solve will be more complex than a simple method. We guarantee a connection within 30 seconds and a customized solution within 20 minutes. Try now. Get instant live expert help with SQL. Enter your problem description Our Experts are available now Your message must be at least 40 characters.Developers are often faced with the need to build a dynamic query, however, there are a number of pitfalls, which we will discuss further in this article.
All current variables are not visible except the temporary tables in a single block of code created by the Execute method. Pay an extra attention while passing variables with a NULL value. Be prepared to the loss of precision while passing the time parameters. To preserve accuracy, it is better to pass values through a temporary table. All string values are potentially dangerous code. All single quotes inside a string must be duplicated. A string itself must be enclosed in single quotation marks.School project proposal example
While inserting a list of values to the IN clause, make sure you are not inserting an empty list. NULL can be compared to any data type. Such comparisons are always result in a negative result, however, the list, in this case, is guaranteed to be non-empty.
It is a good practice to declare variables for all parameters to be passed and then initialize these variables. Then you can use all these variables in the code. It increases the readability and makes debugging easier. In this case, you can explicitly specify the type of variables and get protected from SQL injection attacks.
Here's the created stored procedure:. Conversions follow a specific order of precedence, and generally the more restrictive data type takes precedence. So when you concatenate a datetime column or variable to a string, it tries to convert the string to a datetime. You need to cast or convert the variable to the string datatype. I tried your suggestion and I'm still getting the same error.
When I run the stored procedure to test it I'm passing it the dates like this for now until I get it to pass the parameters from the report:. Okay adjusting the single quotes did the trick. So how is it that the quotes work in this case? It looks like I had to do triple single quotes. In order to embed a single quote inside of single quotes, you have to double the single quote. DVieyra: Welcome to the wonderful world of dynamic sql I dare you Hi, I know the thread is old, but I faced the same problem.
Now everything works fine, thanks for that. To continue this discussion, please ask a new question. Get answers from your peers along with millions of IT pros who visit Spiceworks. Here's the created stored procedure: SQL.How to get rid of rat urine smell under house
Best Answer. Thai Pepper. You need to cast or convert the variable to the string datatype SQL. We found 7 helpful replies in similar discussions:. Fast Answers! Paul Feb 07, Home Categories. Generally we do as following i. Related Articles. Add Comments. Thank you for the feedback. The comment is now awaiting moderation. You will be notified via email when the author replies to your comment. You can add your comment about this article using the form below.
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How to Use Parameters in SQL Server Queries – Querychat
For more details click here. Learn more. How to pass int parameter in dynamic sql query Ask Question. Asked 6 years, 6 months ago. Active 5 years, 3 months ago. Viewed 23k times. I hope you're washing the parameters before calling this, and not taking the keywords parameter from the users, or you have left yourself wide open to sql injection attacks. Karlsen Oct 11 '13 at Oct 11 '13 at No, they didn't.
In the unedited questions the code was just not indented as code so it looked that way. For me it should give an error, but different one, conversion error from int to nvarchar. Have you tried to print or select sqlquery to see what's going on? Active Oldest Votes. Stacky 6 6 silver badges 20 20 bronze badges. I see this solution can't lead to an optimum solution to solve this issue because it will effect on the code writing to implement your sql query. So we will face a problem in maintainability.
Based on the posted code i can only see it would get a conversion error of : Conversion failed when converting the varchar value '' to data type int.
Giannis Paraskevopoulos Giannis Paraskevopoulos Did you check the error? Must declare the scalar variable " SYear". Your code will fail just as the original code failed. When the dynamic query runs they will be treated as int, but in order to form the dynamic query they must be converted. If it were so in the original question, the statement would compile. Check the comments.
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