802 INDEX SELECT, 58, 143–44, 317–68 SET TRANSACTION, 724–25 UPDATE, 58–59, 223–30 State transition model, 670 Static SQL compilation, 756 recompiling, 756–57 Statistics, 509–48 average deviation, 528 AVG() function, 512 cross tabulations, 538–45 cumulative, 528–38 cumulative percentages, 531–33 descriptive, 509 geometric mean, 545–46 harmonic mean, 545–46 median, 512–27 mode, 510–12 multivariable descriptive, 546–48 quintiles, 537–38 rankings, 533–37 running differences, 530–31 running totals, 529–30 standard deviation, 527–28 updating, 760 Storage date, 658 GUID requirement, 42 IP address, 202–5 physically contiguous, 90 temporary table, 51 Strings case, changing, 170–71 character content, 269–70 declaring, 270 defined, 170 dummy, 196 equality, 170–71 expressions, 738 functions, 172–73 grouping, 172 index creation on, 271 length, 172 MAX() function for, 449 MIN() value for, 450 ordering, 171 problems, 170–72 searching, 270 tricks with, 269–71 Subordinates, 635 finding, 630 junior, 635 senior, 635 Subqueries columnar, 257 constants and, 257–58 correlated, 310, 324–26, 436 crosstabs by, 544–45 DEFAULT clauses and, 608 empty, 315 execution, 290 grouped, 362 IN() predicates with, 288 for multiple aggregation levels, 433–34 nesting, 454 in NOT EXISTS() predicates, 435 row, 257, 310 scalar, 257, 433 scalar comparisons, 310–11 SELECT DISTINCT in, 314 table, 433 tabular, 257 TRUE, 315 types of, 257 Subregions, finding, 550–51 Subscripts columns, arrays via, 580–81 data types, 581 in declared range, 580 as enumerations, 585 Subsequences, 549, 554 INDEX 803 Subsets, 605–22 alphabetical ordering, 437 equality, 617–18 minimum, 620 operators, proper, 612–13 proper, equality and, 602–3 representative, picking, 618–22 row, finding, 618 SUBSTRING() function, 172, 467 empty string return, 355 joining tables with, 355 Substrings integer, 485 operator, 381 Subtrees deleting, 630–31, 636–37 finding, 629–30 See also Trees SUM() function, 107, 443–44 ALL keyword, 443 defined, 443 DISTINCT keyword, 470 SUM keyword, 443 Summation of a series, 562–65 complexity, 564 running total, 562 Swaps chain, 95 minimum number of, 95 pairs, 94 Swedish solution, 364 Sybase/SQL Server model, 759 Systematic Treatment of NULL Values, 62 T Tables 3NF, 79 4NF, 76 altering, 628 attribute split, 31–33 auxiliary, 477–507 base, 44 BCNF, 73–74 bitemporal, 164–67 calendar, 567 calendar auxiliary, 673–75 constraints, 5 Cutter, 182–83 cyclic data, 643 deleting in, 216–19 derived, 353–54, 395–97 EKNF, 72, 73 empty, 187 equality, 613–18 flattening, 93 flattening, with VIEWs, 393–95 global constants, 506–7 grouped, 428 indexing, 740–42 loading with query, 355 lookup, 296 manipulating, 5–10 missing, 187 modeling time in, 670–73 name, 5 operations, 211–34 persistent, 3 preserved, 347 random rows, picking, 607–12 redundant duplicates, 217–18 rolling back, 160 schema, 50–51 sequence, 477–85 single-column range, 402–3 spreadsheets vs., 5 temporal granularity, 136 temporary, 51, 390–91, 757–60 timestamped, 131 transaction-time state, 156–58 unpreserved, 347 updating, 97 valid-time state, 136, 145–46 804 INDEX virtual, 3, 369 See also Columns; rows Tabular subqueries, 257 Temporal databases, 135–37 Temporal data models, 129–67 Temporal data types, 119–67 converting, 236 MAX() function for, 449 MIN() function for, 449–50 Temporal duplicates, 129–35 current, 131, 133 defined, 131 interaction, 132 nonsequenced, 133 sequenced, 132, 134, 135 value-equivalent, 132–33 See also Duplicates Temporal JOINs, 139–45 Temporal math, 642–45 Temporal projection/selection, 137–39 Temporal queries, 641–80 calendar auxiliary table, 673–75 date/time extraction functions, 665–66 Julian dates, 661–65 math, 642–43 modeling time in tables, 670–73 personal calendars, 643–45 time series, 645–61 weeks, 667–70 year 2000 problem, 675–80 See also Queries Temporal starting/ending points, 658– 60 Temporal support, 167 Temporary tables, 51 creating, on fly, 393 declarations, 390–91 global, 51, 392 for intermediate results, 757 local, 51, 392 storage space, 51 usefulness, 757–60 using, 392–93 VIEWs and, 391–95 See also Tables Text, in-line expansion, 380–82 Theta operators, 235–40 Third Normal Form (3NF), 71–72 with CASE tools, 78 normalization algorithm, 79 tables, 79 See also Normal forms Three-valued logic (3VL), 193, 306–8 TIME data type, 123, 167 Timelines diagram of overlapping cases, 279 diagrams, 280, 282 partitioned into intervals, 645 Time(s) average wait, 660–61 CUT, 122 DST, 127 durations, 128 fixed events, 128 format, 128 handling, 127–28 handling tips, 124 intervals, 128 missing, in contiguous events, 652–56 modeling in tables, 670–73 overlapping, 277 user-defined, 135 UTC, 122–23, 127, 128 Time series, 645–61 average wait times, 660–61 continuous time periods, 648–52 gaps in, 645–48 locating dates, 656–58 missing times, 652–56 starting/ending points, 658–60 INDEX 805 See also Temporal queries TIMESTAMP data type, 123, 167 time-varying data support with, 167 as unique identifiers, 126 Timestamps handling, 125–27 handling tips, 124 purposes, 125 T-joins, 359–68 approaches, 360–61 Ascending Order Algorithm, 360 Colombian solution, 364–68 condition, maintaining, 361 Croatian solution, 363–64 defined, 359 Descending Order Algorithm, 361 procedural algorithm, 363 Swedish solution, 364 tables, 359–60 See also JOINs Todd’s division, 410–12 Transactions ACID properties and, 720–22 deadlocks, 730 isolation levels, 724–26 livelocks, 730 Transaction-time tables, 156–58 challenge, 156 characterizations, 156–57 example, 157–58 modeling, 156 modifications, 164 nonsequenced queries, 162, 163 sequenced queries, 162, 163 See also Tables Transitive dependencies, 71, 72 3NF and, 71, 72 computed columns, 72 removal, 74 Translated columns, 373–74 TRANSLATE() function, 173 Translation auxiliary tables, 487–88 multiple, 487–88 simple, 487 See also Auxiliary tables Transposition, matrix, 585 Traversal hiding, 628 modified preorder tree algorithm, 633 procedural, 627–28 Trees adjacency list model, 624–28 binary, 623 defined, 623 defining, 624 as directed graphs, 681 edge, deleting, 628 model choices, 639–40 modified preorder, 633 nodes, 623 path enumeration model, 628–31 root, 623 specialized, 639 structure, 624 TRIGGERs, 27 advantages, 53 code, 39–40 declaring, 52–53 defined, 52 disadvantages, 53 performance, 29 uses, 53 Triggers audit logs and, 158 DELETE, 160 INSERT, 160 INSTEAD OF, 28, 36 UPDATE, 160 TRIM() function, 173, 264, 467 TRUNCATE() function, 117, 663, 664 806 INDEX Truncation, 105–6 defined, 105, 444 negative numbers, 444 positive numbers, 444 U UNION ALL operator, 68, 143, 375, 592–96, 617 defined, 592 duplicate preservation, 593 mixed, 595 optimizing, 593 order of execution, 594–95 syntax, 592 See also Set operators UNIONed VIEWs, 375–77 UNION JOINs, 356–57 defined, 350, 356 illustrated, 351 use, 356–57 See also JOINs UNION operator, 142, 143, 375, 592– 96, 617 avoiding, 744 behavior, 602 defined, 592 implementation, 744 mixed, 595 optimizing, 593 order of execution, 594–95 syntax, 592 UNION ALL to replace, 744 See also Set operators UNIQUE constraints, 14, 741 defined, 14 nested, 18–22 UNIQUE indexes vs., 17 UNIQUE indexes, 17 Uniqueness constraints, 31 UNIQUE predicate, 314–15 defined, 314 syntax, 314–15 Universal Coordinated Time (UTC), 122–23, 127, 128 Unload utilities, 223 Updatable VIEWs, 371–73 defined, 371 queries, 372 queries criteria, 371 See also VIEWs Updates audit logs, 158 bitemporal table, 165 logical current, 148–50 with second table, 226–28 sequenced, 152–55 statistics, 760 tables, 97 UPDATE statement, 27, 223–30, 583 with CASE expression, 228–30 defined, 223 error message, 227 FROM clause, 231 positioned, 58–59 searched, 226 with second table, 226–28 SET clause, 224, 225–26 syntax, 223–24 WHERE clause, 224–25, 228, 230 User-controlled keys, 91 USING clause, 327 V Valid-time state tables, 136 current deletion on, 147–48 current modifications, 146–50 current update on, 148–50 modifying, 145–46 nonsequenced modifications, 155 sequenced deletion on, 150–52 sequenced modifications, 150–55 sequenced update on, 152–55 See also Tables Valued predicates, 241–45 INDEX 807 IS [NOT] TRUE | FALSE | UNKNOWN, 242–44 IS NULL, 241–42 Value-equivalent duplicates, 132–33 Value generators, 42–44 Values approximate, 198 average, 445 calibration, 652 insertion, 221 last allocated, 43 missing, 109, 187–90 multiple missing, 199 negative, 114 NULL, multiple, 198–200 preallocated, 44–45 random order, 45–48 seed, 609 sorting, 333 swapping/sliding, 565–67 VALUES constructor, 397, 481 VARCHAR() data type, 169 Vaughan’s median, 519–20 Vendor extensions, 174–82 defined, 174 flaws, 231–32 FLIP(), 175 NUMTOWORDS(), 175 phonetic matching, 175–82 REPLACE(), 174 REPLICATE(), 174 REVERSE(), 175 SPACE(), 174 Vendor math functions, 113–18 exponential functions, 116 numbers to words conversion, 117–18 number theory operators, 113–16 scaling functions, 116–17 VIEWs building, 282, 283–84 calculated columns, 373 changed, 371 defined, 369 definition, 370 dropping, 389–90 existence, 370 flattening, 393–95 GROUP BY clause and, 381, 432 grouped, 290, 374–75 grouped, for multiple aggregation levels, 432 handling in database system, 379– 83 hiding in, 36 indexing and, 383 in-line text expansion, 380–82 JOINs in, 377 key, 371 materialization, 379–80 multitable, 383 names, 370 nested, 370, 377–79 pointer structures, 382–83 in queries, 370 read-only, 371–73, 374 recursive, 688 with schema-level constraints, 25– 29 for security, 392 single-table projection/restriction, 373 syntax, 370 temporary tables and, 391–95 translated columns, 373–74 types of, 373–79 UNIONed, 375–77 updatable, 371–73 Vaughan’s median with, 519–20 WITH CHECK OPTION clause, 383–89 Views 808 INDEX in limiting user access, 45 reconstruction as, 160–61 updating rule, 63 valid-time state, 166 View Updating Rule, 63 Virtual tables, 3 Virtual views. See VIEWs VLDB (Very Large Databases), 39 WWeeks, 667–70 example, 668–69 weekday name sorting, 669–70 WHEN clause CASE expressions, 248, 249, 250 in sequence numbers, 561 WHERE clause complexity, 216 DELETE FROM statement, 212–16 one-level SELECT statement, 318, 323 OUTER JOINs and, 350–51 redundancy, 739 scope rules, 216 UPDATE statement, 224–25, 228, 230 Window clause, 714–16 aggregation grouping, 715–16 format, 714 ordering, 715 partitioning, 715 subclauses, 714 WITH CHECK OPTION clause, 383–89 as CHECK() clause, 388–89 CHECK constraint and, 384 defined, 383 updating and, 385 WHERE clause and, 384 WITH clause derived tables in, 397–99 queries, building, 398 syntax, 397 Words, converting numbers to, 117– 18 X Xbase languages, 171 X/Open transaction model, 757 XOR function, 610 Y Year 2000 problems, 675–80 aftermath, 680 inventory retention programs, 678 leap year, 676–77 legacy data, 679–80 types of, 675 zeros, 675–76 Z Zeller’s algorithm, 666 Zeros, year 2000, 675–76 ABOUT THE AUTHOR Joe Celko is a noted consultant and lecturer, and one of the most- read SQL authors in the world. He is well known for his 10 years of service on the ANSI SQL standards committee, his column in Intelli- gent Enterprise magazine (which won several Reader’s Choice Awards), and the war stories he tells to provide real-world insights into SQL programming. His best-selling books include Joe Celko’s SQL for Smarties: Advanced SQL Programming, second edition; Joe Celko’s SQL Puzzles and Answers; and Joe Celko’s Trees and Hierarchies in SQL for Smarties. . stories he tells to provide real-world insights into SQL programming. His best-selling books include Joe Celko s SQL for Smarties: Advanced SQL Programming, second edition; Joe Celko s SQL Puzzles. 363 Swedish solution, 364 tables, 359–60 See also JOINs Todd s division, 410–12 Transactions ACID properties and, 720–22 deadlocks, 730 isolation levels, 724–26 livelocks, 730 Transaction-time. is well known for his 10 years of service on the ANSI SQL standards committee, his column in Intelli- gent Enterprise magazine (which won several Reader s Choice Awards), and the war stories