First lecture of this chapter is in slides (PPT file)

First lecture of this chapter is in slides (PPT file)

Review of referential integrity CREATE TABLE other_table ( b1 INTEGER, c1 INTEGER, PRIMARY KEY (b1, c1) ) CREATE TABLE t ( a integer PRIMARY KEY, b2 integer, c2 integer, FOREIGN KEY (b, c) REFERENCES other_table (b1, c1) ) Let s say that other_table exists, but does not yet have the primary key defined. How do we add a primary key (or any other constraint) to a table? (p.131)

Let s say that a tuple (b1, c1) is deleted from other_table. What happens to the referencing tuples from t? Let s say that a tuple (b1, c1) is updated in other_table

Actions possible (pp.130-131): RESTRICT / NO ACTION CASCADE SET NULL / SET DEFAULT

CREATE TABLE R ( A INTEGER, B INTEGER ) CREATE ASSERTION ab CHECK ( (SELECT COUNT (*) FROM R AS R1, R AS R2 WHERE (R1.B!= R2.B) AND (R1.A = R2.A)) =0) What exactly does the above assertion imply?

Review of authorization (4.3) Forms of authorization to query/modify DB instance: Read - allows reading, but not modification of data. Insert - allows insertion of new data, but not modification of existing data. Update - allows modification, but not deletion of data. Delete - allows deletion of data. Forms of authorization to modify DB schema (covered in Chapter 8): Index - allows creation and deletion of indices. Resources - allows creation of new relations. Alteration - allows addition or deletion of attributes in a relation. Drop - allows deletion of relations. grant <privilege list> on <relation name or view name> to <user list> grant select on branch to U1, U2, U3 revoke <privilege list> on <relation name or view name> from <user list> revoke select on branch from U1, U2, U3

4.4 Embedded SQL EXEC SQL <embedded SQL statement > END_EXEC EXEC SQL open c END_EXEC EXEC SQL fetch c into :cn, :cc END_EXEC Repeated calls to fetch get successive tuples in the query result A variable called SQLSTATE in the SQL communication area (SQLCA) gets set to 02000 to indicate no more data is available EXEC SQL close c END_EXEC

Example: Add $100 to all account at Perryridge branch. EXEC SQL declare c cursor for select * from account where branch_name = Perryridge for update ; EXEC SQL open c; while(sqlstate!= 02000 ) EXEC SQL update account set balance = balance + 100 where current of c ; EXEC SQL close c;

If you really want to know (not in text, not required) This is the SQLCA in C: #include <SQLCA.H> typedef struct { char sqlcaid[8]; long sqlcabc; long sqlcode; struct { short sqlerrml; char sqlerrmc [70]; } sqlerrm; struct { char sqlwarn0; char sqlwarn1; char sqlwarn2; char sqlwarn3; char sqlwarn4; char sqlwarn5; char sqlwarn6; char sqlwarn7; } sqlwarn char sqlext[8]; } SQLCA; sqlerrml is set to 1 an error has been encountered, otherwise it is set to 0. sqlcode is an integer which is set as follows: o 0 = Statement executed successfully. o < 0 = An error has occurred. The value is the negative of the error number sqlcode = -40202: row containing empty fields encountered. o > 0 = Statement executed successfully but some exceptional condition has occurred, e.g. no data processed (empty field encountered). sqlcode = 100: empty row encountered.

4.5 Dynamic SQL Example of the use of dynamic SQL from within a C program. char * sqlprog = update account set balance = balance * 1.05 where account_number =? EXEC SQL prepare dynprog from :sqlprog; char account [10] = A-101 ; EXEC SQL execute dynprog using :account;

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4.6 Functions and Procedural Constructs in SQL

Since SQL 2003, functions can return tables as well

What is the difference between functions and procedures? Global variable!

Procedural constructs (since SQL 1999):

Can we do this with non-procedural SQL?

Can we do this with non-procedural SQL?

Exception conditions: Explicitely defined (exit, continue, execute_error_handling_function) Predefined (sqlexception, sqlwarning, not found) READ: Extended example on p.149 of text. READ: Section 4.6.3 External Language Routines

4.7 Recursive queries Transitive closure: find all employees managed (directly or indirectly) by Jones

READ and understand the iterative solution (Sec.4.7.1) SKIP Sec. 4.8 Homework for Ch.4: 3, 4, 5, 10, 11, 13 Due next Friday, March 11, before the midterm