IBM -

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3 6.1 q SQL 3

4 q Ø q Ø Ø Ø call level interface q Ø Web 4

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6 6.2 q SQL 6

7 6.2.1 q q Ø Ø Ø Ø 7

8 6.2.2 q q CONNECT TO < > < > < > [AS< >][USER< >] q DISCONNECT < > < > < > ALL CURRENT 8

9 6.2.3 q SQL SQL SQL cursor 9

10 q Cursor Ø declare a cursor Ø open the cursor Ø fetch a row by the cursor One-Row-at-a-Time Principle Ø close the cursor 10

11 6.2.3 q The Declare Cursor Statement EXEC SQL DECLARE cursor-name CURSOR FOR subquery [ ORDER BY... ] [ FOR { READ ONLY UPDATE [ OF columnname,... ] } ] ; Ø Ø SELECT INTO SQL 11

12 6.2.3 qdeclare a cursor define the cursor name EXEC SQL DECLARE agent_dollars CURSOR FOR select aid, sum(dollars) from orders where cid = :cust_id group by aid ; means multiple rows in result set search by customer s id (stored in host variable cust_id) when open the cursor agent_dollars 12

13 qopen the cursor before open the cursor, you must place cno value of customer s id in the host variable cust_id using in the declare statement of cursor agent_dollars. EXEC SQL OPEN agent_dollars ;... execute the select statement after open the cursor, the pointer of the cursor has been placed in the position before the first row in result set. 13

14 qfetch the result rows while (TRUE) { /* loop to fetch rows */ exec sql fetch agent_dollars into :agent_id, :dollar_sum; printf("%s %11.2f\n", agent_id, dollar_sum); } /* end fetch loop */ 1) move the pointer of cursor to the next row, then the next row is current row 2) fetch the current row s value into host variables: agent s id to agent_id, summation of dollars to dollar_sum 14

15 6.2.3 qend fetch loop exec sql whenever not found goto finish;... while (TRUE) { exec sql fetch... into...;... }... finish: exec sql close agent_dollars; declare not found event processing execute this statement after fetch loop when not found event is occur 15

16 6.2.3 qclose the cursor... EXEC SQL CLOSE agent_dollars ;... 1) close the cursor, and release the result set and other resource in DBMS 2) after close the cursor, it can be opened again 16

17 qscrollable Cursors EXEC SQL DECLARE cursor_name [ INSENSITIVE ] [ SCROLL ] CURSOR [ WITH HOLD ] FOR subquery { UNION subquery } [ ORDER BY... ] [ FOR READ ONLY FOR UPDATE OF columnname... ]; EXEC SQL FETCH [ { NEXT PRIOR FIRST LAST { ABSOLUTE RELATIVE } value_spec } FROM ] cursor_name INTO...; 17

18 6.2.4 q Ø Ø

19 6.2.5 SQL 1. SQL Ø SQL SQL SQL SQL SQL 19

20 6.2.5 SQL q SQL Ø SQL Ø Ø Ø SQL q SQL SQL Ø SQL SQL next 20

21 q SQL SQL Ø SQL q SQL Ø SQL SQL 21

22 6.2.5 SQL 2. SQL Ø SQL Ø SQL Ø SQL 22

23 6.2.5 SQL 3. SQL Ø Ø SQL q descriptor area Ø 23

24 3. SQL SQL q Prepare SQL Prepare < > [into <descriptor>] FROM < >; prepare s1 from :mystatement; prepare s2 into :mysqlda from :myquery; 24

25 6.2.5 SQL qdescribe SQL Describe < > into < >; describe s1 into :mysqlda; 25

26 6.2.5 SQL q Execute SQL select Execute < > [ using < > ] Execute s1 Execute s1 using :x, :y Ø SQL q Execute immediate SQL Ø prepare + execute 26

27 4. SQL SQL q SQL EXEC SQL BEGIN DECLARE SECTION; Char stmt[1024]; EXEC SQL END DECLARE SECTION; do { Printf( SQL ); Scanf( %s, &stmt); If (strcmp(stmt, quit ) == 0) break; EXEC SQL EXECUTE IMMEDIATE :stmt ; } while (1); 27

28 6.2.5 SQL q SQL Strcpy(stmt, delete from S where Sn =? ) ; /* */ EXEC SQL PREPARE s1 FROM :stmt ; /* myname */ EXEC SQL EXECUTE s1 USING :myname ; /* myname */ 28

29 6.2.5 SQL q SQL Ø prepare SQL Ø EXEC SQL DECLARE < > CURSOR FOR < > ; Ø EXEC SQL OPEN < > [ USING < > ] ; Ø EXEC SQL FETCH INTO < > USING DESCRIPTOR < >; Ø 29

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33 SQL SQL Web 33

34 q SQL Ø SQL SQL Ø SQL SQL+ Ø SQL SQL 34

35 6.4.1 SQL q SQL 1. SQL 2. SQL 3. SQL 4. SQL 35

36 6.4.1 SQL 1. SQL Ø SQL EXEC SQL END_EXEC 2. ESQL EXEC SQL INCLUDE SQLCA; SQLCA SQL 36

37 6.4.1 SQL 3. SQL Ø SQL Ø SQL SQL SQL Ø SQL Ø SQL : SQL 37

38 6.4.1 SQL q SQL Ø Ø SQL 38

39 6.4.1 SQL q SQL DECLARE EXEC SQL BEGIN DECLARE SECTION; /* SQL */ EXEC SQL END DECLARE SECTION; 39

40 6.4.1 SQL 4. SQL Ø SQL cursor Ø SQL SQL 40

41 SQL 1 EXEC SQL select count(*) into :host_var from customers ; q SQL Ø EXEC SQL ; Ø into Ø :host_var : SQL 41

42 SQL 2 EXEC SQL select cname, discnt into :cust_name, :cust_discnt from customers where cid = :cust_id ; q DECLARE SECTION Why q DECLARE SECTION Ø Ø 42

43 SQL q The Declare Section Ø q Condition Handling Ø SQL q SQL Connect to Database Ø q Main Body of Application Program Ø Ø ESQL q SQL Disconnect Ø 43

44 The Declare Section exec sql begin declare section; char cust_id[5]; char cust_name[14]; float cust_discnt; char user_name[20], user_pwd[20]; exec sql end declare section; Begin declare SQL host variables host variables for cno, four characters and a null terminator End of declare section host variables for user name and password 44

45 Condition Handling exec sql whenever sqlerror goto report_error; exec sql whenever not found goto notfound; error trap condition not found condition 45

46 q SQL99 SQL Connect Statement EXEC SQL CONNECT TO target-server [AS connect-name] [USER username] ; EXEC SQL CONNECT TO DEFAULT ; Ø target-server Ø connect-name connect session Ø username 46

47 SQL Connect Statement q Oracle EXEC SQL CONNECT TO :user_name IDENTIFIED BY :user_pwd ; Ø user_name Oracle Ø user_pwd Ø Oracle 47

48 while (prompt(cid_prompt, 1, cust_id, 4) >= 0) { exec sql select cname, discnt into :cust_name, :cust_discnt from customers cust_id where cid = :cust_id; exec sql commit work; printf("customer's NAME IS %s AND DISCNT IS %5.1f\n", cust_name, cust_discnt); continue; notfound: printf("can't find customer %s, continuing\n", cust_id); } 48

49 SQL Disconnect Statement q SQL99 EXEC SQL DISCONNECT connect-name ; or EXEC SQL DISCONNECT CURRENT ; Ø Commit Rollback EXEC SQL COMMIT WORK ; EXEC SQL ROLLBACK WORK ; 49

50 qoracle SQL Disconnect Statement exec sql commit release ; exec sql rollback release ; a rollback statement followed by a disconnect statement, to undo any partial work in an unsuccessful task a commit statement followed by a disconnect statement, for successful completion 50

51 SQL q SQL Ø Precompiler DBMS SQL Ø Compiler Ø Ø 51

52 6.4.2 SQL q SQL Ø SQL Ø Ø SQL SQL 52

53 SQL q SQL * / DECLARE /* */ BEGIN EXCEPTION /* */ END 53

54 SQL q SQL SQL Ø SQL Ø 54

55 6.4.3 q C/S Ø ISO SQL/CLI Ø ODBC Ø SUN JDBC q Ø Ø Ø 55

56 q Ø Ø AlloEnv SQL AlloStmt SQL AlloHandle SQL AlloConnect SQL Connect 56

57 6.4.3 q Ø SQL 57

58 q Ø

59 ODBC 1 SQLAllocEnv SQLAllocConnect SQLAllocConnect SQLAllocConnect SQLConnect SQLConnect SQLConnect SQLAllocStmt SQLAllocStmt SQLAllocStmt 59

60 ODBC 2 SQLAllocStmt SQLPrepare SQLExecDirect SQLExecute SQL Get SQL Fetch SQL Get SQLFreeStmt 60

61 ODBC 3 SQLFreeStmt SQLDisConnect SQLFreeConnect SQLFreeEnv 61

62 6.4.4 Web q ASP q JSP q XML 62

63 q q q 63

64 q q q 64

65 JDBC q Class.forName( com.mysql.jdbc.driver ); Connection conn = Driver.Manager.getConnection( url, user, password ); conn.close(); q Statement, PreparedStatement & addbatch() q ResultSet & ResultSetMetaData q SQLException 65

66 JDBC BasicDataSource ds = new BasicDataSource(); ds.setdriverclassname(dbparam.drv); ds.seturl(dbparam.url); ds.setusername(dbparam.usr); ds.setpassword(dbparam.pwd); dssetmaxactive(16); ds.setmaxidle(2); ds.setdefaulttransactionisolation( Connection.TRANSACTION_SERIALIZABLE); ds.settestonborrow(true); String sqlstr = "SHOW TABLES"; ds.setvalidationquery(sqlstr); 66