The Query Compiler Varun Sud ID: 104

Agenda Parsing  Syntax analysis and Parse Trees.  Grammar for a simple subset of SQL  Base Syntactic Categories  The Preprocessor.

Parsing Three steps of query processor  Parse SQL query into parse tree.  Transform parse tree into expression tree.  Transform logical query plan into physical query plan.

Syntax analysis and parse trees Parser converts SQL text to parse tree  Nodes of trees correspond to: Atoms: lexical elements such as keywords, names of attributes or relations etc Syntactic categories, which are names of families of query subparts.

Grammar for simple subset of SQL Queries  ::=  ::= ( ) SFW: select from were ::= means “can be expressed as.”

Contd. Select-From-Where Forms  ::= SELECT FROM WHERE Select-Lists  ::=,  ::=

Contd. Conditions  ::= AND  ::= IN  ::= =  ::= LIKE  ::=

The Preprocessor Preprocessor is responsible for semantic checking. Preprocessor must:  Check relation uses.  Check and resolve attribute uses  Check types.

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