Notes01 - CS 245 Notes 1 1 CS 245: Database System...

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Unformatted text preview: CS 245 Notes 1 1 CS 245: Database System Principles Notes 01: Introduction Steven Whang CS 245 Notes 1 2 Isnt Implementing a Database System Simple? Relations Statements Results CS 245 Notes 1 3 Introducing the Database Management System The latest from Megatron Labs Incorporates latest relational technology UNIX compatible CS 245 Notes 1 4 Megatron 3000 Implementation Details First sign non-disclosure agreement CS 245 Notes 1 5 Megatron 3000 Implementation Details Relations stored in files (ASCII) e.g., relation R is in /usr/db/R Smith # 123 # CS Jones # 522 # EE . . . CS 245 Notes 1 6 Megatron 3000 Implementation Details Directory file (ASCII) in /usr/db/directory R1 # A # INT # B # STR R2 # C # STR # A # INT . . . CS 245 Notes 1 7 Megatron 3000 Sample Sessions % MEGATRON3000 Welcome to MEGATRON 3000! & & quit % . . . CS 245 Notes 1 8 Megatron 3000 Sample Sessions & select * from R # Relation R A B C SMITH 123 CS & CS 245 Notes 1 9 Megatron 3000 Sample Sessions & select A,B from R,S where R.A = S.A and S.C > 100 # A B 123 CAR 522 CAT & CS 245 Notes 1 10 Megatron 3000 Sample Sessions & select * from R | LPR # & Result sent to LPR (printer). CS 245 Notes 1 11 Megatron 3000 Sample Sessions & select * from R where R.A < 100 | T # & New relation T created. CS 245 Notes 1 12 Megatron 3000 To execute select * from R where condition : (1) Read dictionary to get R attributes (2) Read R file, for each line: (a) Check condition (b) If OK, display CS 245 Notes 1 7 Megatron 3000 Sample Sessions % MEGATRON3000 Welcome to MEGATRON 3000! & & quit % . . . CS 245 Notes 1 8 Megatron 3000 Sample Sessions & select * from R # Relation R A B C SMITH 123 CS & CS 245 Notes 1 9 Megatron 3000 Sample Sessions & select A,B from R,S where R.A = S.A and S.C > 100 # A B 123 CAR 522 CAT & CS 245 Notes 1 10 Megatron 3000 Sample Sessions & select * from R | LPR # & Result sent to LPR (printer)....
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Notes01 - CS 245 Notes 1 1 CS 245: Database System...

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