Parsing technique in sql server

Introduction

Background

1. Lexical phase - Code break up will happen at this stage. All my code breaks up as individual tokens.
   Let us consider
   
   Code:

    int a;

   The code gets broken like "int" as a separate token and "a" as a seperate token.
   
2. Syntax analysis - Here my code gets checked for its syntax.
   
   In C program we have a standard rule like, if i want to declare a variable we have to specify the variable and followed by variable name and you can specify the values(initialization) followed by semicolor (
   
   Code:

   int i=0;

   In sql server the syntax for select statement is,
   
   Code:

      select colname from tablename where condition on the columns

3. Semantic phase - Here the semantics will be checked. For example i am trying to execute a simple piece of code in c#,
   
   
   Code:

     Console.Writeline(a.ToString());
     int a;

   In the above code my syntax is correct and i have missed my semantics because i am trying to print the variable a with out declaring it and i am declaring the same after printing it.
   
4. Intermediate code generation - Its the fourth stage where an intermediate code will be generated by the compiler its like converting the high level code to machine level code.
   
5. Code Optimization - My compiler will holds some optimization technique to optimize the code so that we can achieve effective execution of our code.
   
6. Optimized code generation - After code optimization a final code will be generated which can be used to retrieve the data. In sql server this optimized code will be stored and used frequently to fetch the data from the database.
   
7. Code execution - The optimized code gets executed against the database engine.