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    <p>This is a question about scope.</p> <p>Basicly, in C#, when you open a new set of <code>{}</code>, you declare a new scope. Variable create within that scope, are destroyed when exiting it. It is a fairly simplify explanation, not fully accurate, but it is an easy one to understand.</p> <pre><code>{ var testVariable = "blah"; //set cache key and query based their being a craft name if(testVariable.Length &gt; 0) { var db = Database.Open("Connection"); // Create a new variable. var selectedData = db.Query("SELECT * FROM Products"); } // Variable doesn't exist anymore. } </code></pre> <p>To fix it:</p> <pre><code>{ var testVariable = "blah"; // Create variable outside the if scope var selectedData = null; // Won't compile, compiler cannot find valid variable type. //set cache key and query based their being a craft name if(testVariable.Length &gt; 0) { var db = Database.Open("Connection"); // Assign a value to a variable selectedData = db.Query("SELECT * FROM Products"); } // Variable still exist! } // Here, variable would cease to exist. :( </code></pre> <p>But here, the code won't compile, because the compile doesn't know what type <code>selectedData</code> is, because I assign it <code>null</code>  at its creation. So, let's say <code>selectedData</code> is of type <code>Data</code>:</p> <pre><code>{ var testVariable = "blah"; // Create variable outside the if scope Data selectedData = null; // Now it compiles. :) //set cache key and query based their being a craft name if(testVariable.Length &gt; 0) { var db = Database.Open("Connection"); // Assign a value to a variable selectedData = db.Query("SELECT * FROM Products"); } // Variable still exist! } // Here, variable would cease to exist. :( </code></pre> <p>After that, you can do <code>if (selectedData != null)</code> to know if the data was correctly queried.</p>
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    1. POC# - How can I declare a variable that will get populated by a database call inside an if statement?
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    1. USLightStriker
    1. USLightStriker
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    1. COYou should note that this won't actually compile as well.
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      1. USJordan Kaye
    2. CO@JordanKaye: Most likely. I still have a hard time to understand why people spam `var` all over the place. It just make tracking of variable type harder.
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      1. USLightStriker
    3. COThis will be the error CS0818 - "Implicitly-typed local variables must be initialized"
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      1. USseth flowers
 

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