Oracle之函数concat、lpad
一、引言
程序测试需要生成大量的测试数据，且测试数据有主键，主键自增，于是决定用存储过程来实现，经过半天的查资料终于完成了，记录之，学习之
二、存储过程
格式：
CREATE PROCEDURE remove_emp (employee_id NUMBER) AS tot_emps NUMBER; BEGIN DELETE FROM employees WHERE employees.employee_id = remove_emp.employee_id; tot_emps := tot_emps - 1; END; /
三、函数
意外发现Oracle有许多好用的函数，此次就使用到了两个函数：
concat
CONCAT Syntax Description of concat.gif follows Description of the illustration concat.gif Purpose CONCAT returns char1 concatenated with char2. Both char1 and char2 can be any of the datatypes CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB. The string returned is in the same character set as char1. Its datatype depends on the datatypes of the arguments. In concatenations of two different datatypes, Oracle Database returns the datatype that results in a lossless conversion. Therefore, if one of the arguments is a LOB, then the returned value is a LOB. If one of the arguments is a national datatype, then the returned value is a national datatype. For example: CONCAT(CLOB, NCLOB) returns NCLOB CONCAT(NCLOB, NCHAR) returns NCLOB CONCAT(NCLOB, CHAR) returns NCLOB CONCAT(NCHAR, CLOB) returns NCLOB This function is equivalent to the concatenation operator (||). See Also: "Concatenation Operator" for information on the CONCAT operator Examples This example uses nesting to concatenate three character strings: SELECT CONCAT(CONCAT(last_name, '''s job category is '), job_id) "Job" FROM employees WHERE employee_id = 152; Job ------------------------------------------------------ Hall's job category is SA_REP
lpad
LPAD The LPAD function returns an expression, left-padded to a specified length with the specified characters; or, when the expression to be padded is longer than the length specified after padding, only that portion of the expression that fits into the specified length. To right-pad a text expression, use RPAD. Return Value TEXT or NTEXT based on the data type of the expression you want to pad (text-exp). Syntax LPAD (text-exp , length [, pad-exp]) Arguments text-exp A text expression that you want to pad. length The total length of the return value as it is displayed on your screen. In most character sets, this is also the number of characters in the return value. However, in some multibyte character sets, the display length of a character string can differ from the number of characters in the string. When you specify a value for length that is shorter than the length of text-exp, then this function returns only that portion of the expression that fits into the specified length. pad-exp A text expression that specifies the padding characters. The default value of pad-exp is a single blank. Examples The following example left-pads a string with the characters "*" and ".". SHOW LPAD('Page 1',15,'*.') *.*.*.*.*Page 1
生成自增索引列的代码就是：
concat('1234', lpad(i, 18, 0))
生成规则是，以1234开头，后跟18位自增数字的字符串
注意：使用concat函数时，里面的字符串如果是"引起的，则会提示错误，这个应该跟Oracle中'和"的用法区别有关，没有深入了解，不知道什么原因。
参考：Oracle函数大全
1 SQL中的单记录函数 2 1.ASCII 3 返回与指定的字符对应的十进制数; 4 SQL> select ascii('A') A,ascii('a') a,ascii('0') zero,ascii(' ') space from dual; 5 6 A A ZERO SPACE 7 --------- --------- --------- --------- 8 65 97 48 32 9 10 11 2.CHR 12 给出整数,返回对应的字符; 13 SQL> select chr(54740) zhao,chr(65) chr65 from dual; 14 15 ZH C 16 -- - 17 赵 A 18 19 3.CONCAT 20 连接两个字符串; 21 SQL> select concat('010-','88888888')||'转23' 高乾竞电话 from dual; 22 23 高乾竞电话 24 ---------------- 25 010-88888888转23 26 27 4.INITCAP 28 返回字符串并将字符串的第一个字母变为大写; 29 SQL> select initcap('smith') upp from dual; 30 31 UPP 32 ----- 33 Smith 34 35 36 5.INSTR(C1,C2,I,J) 37 在一个字符串中搜索指定的字符,返回发现指定的字符的位置; 38 C1 被搜索的字符串 39 C2 希望搜索的字符串 40 I 搜索的开始位置,默认为1 41 J 出现的位置,默认为1 42 SQL> select instr('oracle traning','ra',1,2) instring from dual; 43 44 INSTRING 45 --------- 46 9 47 48 49 6.LENGTH 50 返回字符串的长度; 51 SQL> select name,length(name),addr,length(addr),sal,length(to_char(sal)) from gao.nchar_tst; 52 53 NAME LENGTH(NAME) ADDR LENGTH(ADDR) SAL LENGTH(TO_CHAR(SAL)) 54 ------ ------------ ---------------- ------------ --------- -------------------- 55 高乾竞 3 北京市海锭区 6 9999.99 7 56 57 58 59 7.LOWER 60 返回字符串,并将所有的字符小写 61 SQL> select lower('AaBbCcDd')AaBbCcDd from dual; 62 63 AABBCCDD 64 -------- 65 aabbccdd 66 67 68 8.UPPER 69 返回字符串,并将所有的字符大写 70 SQL> select upper('AaBbCcDd') upper from dual; 71 72 UPPER 73 -------- 74 AABBCCDD 75 76 77 78 9.RPAD和LPAD(粘贴字符) 79 RPAD 在列的右边粘贴字符 80 LPAD 在列的左边粘贴字符 81 SQL> select lpad(rpad('gao',10,'*'),17,'*')from dual; 82 83 LPAD(RPAD('GAO',1 84 ----------------- 85 *******gao******* 86 不够字符则用*来填满 87 88 89 10.LTRIM和RTRIM 90 LTRIM 删除左边出现的字符串 91 RTRIM 删除右边出现的字符串 92 SQL> select ltrim(rtrim(' gao qian jing ',' '),' ') from dual; 93 94 LTRIM(RTRIM(' 95 ------------- 96 gao qian jing 97 98 99 11.SUBSTR(string,start,count) 100 取子字符串,从start开始,取count个 101 SQL> select substr('13088888888',3,8) from dual; 102 103 SUBSTR(' 104 -------- 105 08888888 106 107 108 12.REPLACE('string','s1','s2') 109 string 希望被替换的字符或变量 110 s1 被替换的字符串 111 s2 要替换的字符串 112 SQL> select replace('he love you','he','i') from dual; 113 114 REPLACE('H 115 ---------- 116 i love you 117 118 119 13.SOUNDEX 120 返回一个与给定的字符串读音相同的字符串 121 SQL> create table table1(xm varchar(8)); 122 SQL> insert into table1 values('weather'); 123 SQL> insert into table1 values('wether'); 124 SQL> insert into table1 values('gao'); 125 126 SQL> select xm from table1 where soundex(xm)=soundex('weather'); 127 128 XM 129 -------- 130 weather 131 wether 132 133 134 14.TRIM('s' from 'string') 135 LEADING 剪掉前面的字符 136 TRAILING 剪掉后面的字符 137 如果不指定,默认为空格符 138 139 15.ABS 140 返回指定值的绝对值 141 SQL> select abs(100),abs(-100) from dual; 142 143 ABS(100) ABS(-100) 144 --------- --------- 145 100 100 146 147 148 16.ACOS 149 给出反余弦的值 150 SQL> select acos(-1) from dual; 151 152 ACOS(-1) 153 --------- 154 3.1415927 155 156 157 17.ASIN 158 给出反正弦的值 159 SQL> select asin(0.5) from dual; 160 161 ASIN(0.5) 162 --------- 163 .52359878 164 165 166 18.ATAN 167 返回一个数字的反正切值 168 SQL> select atan(1) from dual; 169 170 ATAN(1) 171 --------- 172 .78539816 173 174 175 19.CEIL 176 返回大于或等于给出数字的最小整数 177 SQL> select ceil(3.1415927) from dual; 178 179 CEIL(3.1415927) 180 --------------- 181 4 182 183 184 20.COS 185 返回一个给定数字的余弦 186 SQL> select cos(-3.1415927) from dual; 187 188 COS(-3.1415927) 189 --------------- 190 -1 191 192 193 21.COSH 194 返回一个数字反余弦值 195 SQL> select cosh(20) from dual; 196 197 COSH(20) 198 --------- 199 242582598 200 201 202 22.EXP 203 返回一个数字e的n次方根 204 SQL> select exp(2),exp(1) from dual; 205 206 EXP(2) EXP(1) 207 --------- --------- 208 7.3890561 2.7182818 209 210 211 23.FLOOR 212 对给定的数字取整数 213 SQL> select floor(2345.67) from dual; 214 215 FLOOR(2345.67) 216 -------------- 217 2345 218 219 220 24.LN 221 返回一个数字的对数值 222 SQL> select ln(1),ln(2),ln(2.7182818) from dual; 223 224 LN(1) LN(2) LN(2.7182818) 225 --------- --------- ------------- 226 0 .69314718 .99999999 227 228 229 25.LOG(n1,n2) 230 返回一个以n1为底n2的对数 231 SQL> select log(2,1),log(2,4) from dual; 232 233 LOG(2,1) LOG(2,4) 234 --------- --------- 235 0 2 236 237 238 26.MOD(n1,n2) 239 返回一个n1除以n2的余数 240 SQL> select mod(10,3),mod(3,3),mod(2,3) from dual; 241 242 MOD(10,3) MOD(3,3) MOD(2,3) 243 --------- --------- --------- 244 1 0 2 245 246 247 27.POWER 248 返回n1的n2次方根 249 SQL> select power(2,10),power(3,3) from dual; 250 251 POWER(2,10) POWER(3,3) 252 ----------- ---------- 253 1024 27 254 255 256 28.ROUND和TRUNC 257 按照指定的精度进行舍入 258 SQL> select round(55.5),round(-55.4),trunc(55.5),trunc(-55.5) from dual; 259 260 ROUND(55.5) ROUND(-55.4) TRUNC(55.5) TRUNC(-55.5) 261 ----------- ------------ ----------- ------------ 262 56 -55 55 -55 263 264 265 29.SIGN 266 取数字n的符号,大于0返回1,小于0返回-1,等于0返回0 267 SQL> select sign(123),sign(-100),sign(0) from dual; 268 269 SIGN(123) SIGN(-100) SIGN(0) 270 --------- ---------- --------- 271 1 -1 0 272 273 274 30.SIN 275 返回一个数字的正弦值 276 SQL> select sin(1.57079) from dual; 277 278 SIN(1.57079) 279 ------------ 280 1 281 282 283 31.SIGH 284 返回双曲正弦的值 285 SQL> select sin(20),sinh(20) from dual; 286 287 SIN(20) SINH(20) 288 --------- --------- 289 .91294525 242582598 290 291 292 32.SQRT 293 返回数字n的根 294 SQL> select sqrt(64),sqrt(10) from dual; 295 296 SQRT(64) SQRT(10) 297 --------- --------- 298 8 3.1622777 299 300 301 33.TAN 302 返回数字的正切值 303 SQL> select tan(20),tan(10) from dual; 304 305 TAN(20) TAN(10) 306 --------- --------- 307 2.2371609 .64836083 308 309 310 34.TANH 311 返回数字n的双曲正切值 312 SQL> select tanh(20),tan(20) from dual; 313 314 TANH(20) TAN(20) 315 --------- --------- 316 1 2.2371609 317 318 319 320 35.TRUNC 321 按照指定的精度截取一个数 322 SQL> select trunc(124.1666,-2) trunc1,trunc(124.16666,2) from dual; 323 324 TRUNC1 TRUNC(124.16666,2) 325 --------- ------------------ 326 100 124.16 327 328 329 330 36.ADD_MONTHS 331 增加或减去月份 332 SQL> select to_char(add_months(to_date('199912','yyyymm'),2),'yyyymm') from dual; 333 334 TO_CHA 335 ------ 336 200002 337 SQL> select to_char(add_months(to_date('199912','yyyymm'),-2),'yyyymm') from dual; 338 339 TO_CHA 340 ------ 341 199910 342 343 344 37.LAST_DAY 345 返回日期的最后一天 346 SQL> select to_char(sysdate,'yyyy.mm.dd'),to_char((sysdate)+1,'yyyy.mm.dd') from dual; 347 348 TO_CHAR(SY TO_CHAR((S 349 ---------- ---------- 350 2004.05.09 2004.05.10 351 SQL> select last_day(sysdate) from dual; 352 353 LAST_DAY(S 354 ---------- 355 31-5月 -04 356 357 358 38.MONTHS_BETWEEN(date2,date1) 359 给出date2-date1的月份 360 SQL> select months_between('19-12月-1999','19-3月-1999') mon_between from dual; 361 362 MON_BETWEEN 363 ----------- 364 9 365 SQL>selectmonths_between(to_date('2000.05.20','yyyy.mm.dd'),to_date('2005.05.20','yyyy.mm.dd')) mon_betw from dual; 366 367 MON_BETW 368 --------- 369 -60 370 371 372 39.NEW_TIME(date,'this','that') 373 给出在this时区=other时区的日期和时间 374 SQL> select to_char(sysdate,'yyyy.mm.dd hh24:mi:ss') bj_time,to_char(new_time 375 2 (sysdate,'PDT','GMT'),'yyyy.mm.dd hh24:mi:ss') los_angles from dual; 376 377 BJ_TIME LOS_ANGLES 378 ------------------- ------------------- 379 2004.05.09 11:05:32 2004.05.09 18:05:32 380 381 382 40.NEXT_DAY(date,'day') 383 给出日期date和星期x之后计算下一个星期的日期 384 SQL> select next_day('18-5月-2001','星期五') next_day from dual; 385 386 NEXT_DAY 387 ---------- 388 25-5月 -01 389 390 391 392 41.SYSDATE 393 用来得到系统的当前日期 394 SQL> select to_char(sysdate,'dd-mm-yyyy day') from dual; 395 396 TO_CHAR(SYSDATE,' 397 ----------------- 398 09-05-2004 星期日 399 trunc(date,fmt)按照给出的要求将日期截断,如果fmt='mi'表示保留分,截断秒 400 SQL> select to_char(trunc(sysdate,'hh'),'yyyy.mm.dd hh24:mi:ss') hh, 401 2 to_char(trunc(sysdate,'mi'),'yyyy.mm.dd hh24:mi:ss') hhmm from dual; 402 403 HH HHMM 404 ------------------- ------------------- 405 2004.05.09 11:00:00 2004.05.09 11:17:00 406 407 408 409 42.CHARTOROWID 410 将字符数据类型转换为ROWID类型 411 SQL> select rowid,rowidtochar(rowid),ename from scott.emp; 412 413 ROWID ROWIDTOCHAR(ROWID) ENAME 414 ------------------ ------------------ ---------- 415 AAAAfKAACAAAAEqAAA AAAAfKAACAAAAEqAAA SMITH 416 AAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLEN 417 AAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARD 418 AAAAfKAACAAAAEqAAD AAAAfKAACAAAAEqAAD JONES 419 420 421 43.CONVERT(c,dset,sset) 422 将源字符串 sset从一个语言字符集转换到另一个目的dset字符集 423 SQL> select convert('strutz','we8hp','f7dec') "conversion" from dual; 424 425 conver 426 ------ 427 strutz 428 429 430 44.HEXTORAW 431 将一个十六进制构成的字符串转换为二进制 432 433 434 45.RAWTOHEXT 435 将一个二进制构成的字符串转换为十六进制 436 437 438 439 46.ROWIDTOCHAR 440 将ROWID数据类型转换为字符类型 441 442 443 444 47.TO_CHAR(date,'format') 445 SQL> select to_char(sysdate,'yyyy/mm/dd hh24:mi:ss') from dual; 446 447 TO_CHAR(SYSDATE,'YY 448 ------------------- 449 2004/05/09 21:14:41 450 451 452 453 48.TO_DATE(string,'format') 454 将字符串转化为ORACLE中的一个日期 455 456 457 49.TO_MULTI_BYTE 458 将字符串中的单字节字符转化为多字节字符 459 SQL> select to_multi_byte('高') from dual; 460 461 TO 462 -- 463 高 464 465 466 50.TO_NUMBER 467 将给出的字符转换为数字 468 SQL> select to_number('1999') year from dual; 469 470 YEAR 471 --------- 472 1999 473 474 475 51.BFILENAME(dir,file) 476 指定一个外部二进制文件 477 SQL>insert into file_tb1 values(bfilename('lob_dir1','image1.gif')); 478 479 480 52.CONVERT('x','desc','source') 481 将x字段或变量的源source转换为desc 482 SQL> select sid,serial#,username,decode(command, 483 2 0,'none', 484 3 2,'insert', 485 4 3, 486 5 'select', 487 6 6,'update', 488 7 7,'delete', 489 8 8,'drop', 490 9 'other') cmd from v$session where type!='background'; 491 492 SID SERIAL# USERNAME CMD 493 --------- --------- ------------------------------ ------ 494 1 1 none 495 2 1 none 496 3 1 none 497 4 1 none 498 5 1 none 499 6 1 none 500 7 1275 none 501 8 1275 none 502 9 20 GAO select 503 10 40 GAO none 504 505 506 53.DUMP(s,fmt,start,length) 507 DUMP函数以fmt指定的内部数字格式返回一个VARCHAR2类型的值 508 SQL> col global_name for a30 509 SQL> col dump_string for a50 510 SQL> set lin 200 511 SQL> select global_name,dump(global_name,1017,8,5) dump_string from global_name; 512 513 GLOBAL_NAME DUMP_STRING 514 ------------------------------ -------------------------------------------------- 515 ORACLE.WORLD Typ=1 Len=12 CharacterSet=ZHS16GBK: W,O,R,L,D 516 517 518 54.EMPTY_BLOB()和EMPTY_CLOB() 519 这两个函数都是用来对大数据类型字段进行初始化操作的函数 520 521 522 55.GREATEST 523 返回一组表达式中的最大值,即比较字符的编码大小. 524 SQL> select greatest('AA','AB','AC') from dual; 525 526 GR 527 -- 528 AC 529 SQL> select greatest('啊','安','天') from dual; 530 531 GR 532 -- 533 天 534 535 536 56.LEAST 537 返回一组表达式中的最小值 538 SQL> select least('啊','安','天') from dual; 539 540 LE 541 -- 542 啊 543 544 545 57.UID 546 返回标识当前用户的唯一整数 547 SQL> show user 548 USER 为"GAO" 549 SQL> select username,user_id from dba_users where user_id=uid; 550 551 USERNAME USER_ID 552 ------------------------------ --------- 553 GAO 25 554 555 556 557 58.USER 558 返回当前用户的名字 559 SQL> select user from dual; 560 561 USER 562 ------------------------------ 563 GAO 564 565 566 59.USEREVN 567 返回当前用户环境的信息,opt可以是: 568 ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE 569 ISDBA 查看当前用户是否是DBA如果是则返回true 570 SQL> select userenv('isdba') from dual; 571 572 USEREN 573 ------ 574 FALSE 575 SQL> select userenv('isdba') from dual; 576 577 USEREN 578 ------ 579 TRUE 580 SESSION 581 返回会话标志 582 SQL> select userenv('sessionid') from dual; 583 584 USERENV('SESSIONID') 585 -------------------- 586 152 587 ENTRYID 588 返回会话人口标志 589 SQL> select userenv('entryid') from dual; 590 591 USERENV('ENTRYID') 592 ------------------ 593 0 594 INSTANCE 595 返回当前INSTANCE的标志 596 SQL> select userenv('instance') from dual; 597 598 USERENV('INSTANCE') 599 ------------------- 600 1 601 LANGUAGE 602 返回当前环境变量 603 SQL> select userenv('language') from dual; 604 605 USERENV('LANGUAGE') 606 ---------------------------------------------------- 607 SIMPLIFIED CHINESE_CHINA.ZHS16GBK 608 LANG 609 返回当前环境的语言的缩写 610 SQL> select userenv('lang') from dual; 611 612 USERENV('LANG') 613 ---------------------------------------------------- 614 ZHS 615 TERMINAL 616 返回用户的终端或机器的标志 617 SQL> select userenv('terminal') from dual; 618 619 USERENV('TERMINA 620 ---------------- 621 GAO 622 VSIZE(X) 623 返回X的大小(字节)数 624 SQL> select vsize(user),user from dual; 625 626 VSIZE(USER) USER 627 ----------- ------------------------------ 628 6 SYSTEM 629 630 631 632 60.AVG(DISTINCT|ALL) 633 all表示对所有的值求平均值,distinct只对不同的值求平均值 634 SQLWKS> create table table3(xm varchar(8),sal number(7,2)); 635 语句已处理。 636 SQLWKS> insert into table3 values('gao',1111.11); 637 SQLWKS> insert into table3 values('gao',1111.11); 638 SQLWKS> insert into table3 values('zhu',5555.55); 639 SQLWKS> commit; 640 641 SQL> select avg(distinct sal) from gao.table3; 642 643 AVG(DISTINCTSAL) 644 ---------------- 645 3333.33 646 647 SQL> select avg(all sal) from gao.table3; 648 649 AVG(ALLSAL) 650 ----------- 651 2592.59 652 653 654 61.MAX(DISTINCT|ALL) 655 求最大值,ALL表示对所有的值求最大值,DISTINCT表示对不同的值求最大值,相同的只取一次 656 SQL> select max(distinct sal) from scott.emp; 657 658 MAX(DISTINCTSAL) 659 ---------------- 660 5000 661 662 663 62.MIN(DISTINCT|ALL) 664 求最小值,ALL表示对所有的值求最小值,DISTINCT表示对不同的值求最小值,相同的只取一次 665 SQL> select min(all sal) from gao.table3; 666 667 MIN(ALLSAL) 668 ----------- 669 1111.11 670 671 672 63.STDDEV(distinct|all) 673 求标准差,ALL表示对所有的值求标准差,DISTINCT表示只对不同的值求标准差 674 SQL> select stddev(sal) from scott.emp; 675 676 STDDEV(SAL) 677 ----------- 678 1182.5032 679 680 SQL> select stddev(distinct sal) from scott.emp; 681 682 STDDEV(DISTINCTSAL) 683 ------------------- 684 1229.951 685 686 687 688 64.VARIANCE(DISTINCT|ALL) 689 求协方差 690 691 SQL> select variance(sal) from scott.emp; 692 693 VARIANCE(SAL) 694 ------------- 695 1398313.9 696 697 698 65.GROUP BY 699 主要用来对一组数进行统计 700 SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno; 701 702 DEPTNO COUNT(*) SUM(SAL) 703 --------- --------- --------- 704 10 3 8750 705 20 5 10875 706 30 6 9400 707 708 709 710 66.HAVING 711 对分组统计再加限制条件 712 SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno having count(*)>=5; 713 714 DEPTNO COUNT(*) SUM(SAL) 715 --------- --------- --------- 716 20 5 10875 717 30 6 9400 718 SQL> select deptno,count(*),sum(sal) from scott.emp having count(*)>=5 group by deptno ; 719 720 DEPTNO COUNT(*) SUM(SAL) 721 --------- --------- --------- 722 20 5 10875 723 30 6 9400 724 725 726 67.ORDER BY 727 用于对查询到的结果进行排序输出 728 SQL> select deptno,ename,sal from scott.emp order by deptno,sal desc; 729 730 DEPTNO ENAME SAL 731 --------- ---------- --------- 732 10 KING 5000 733 10 CLARK 2450 734 10 MILLER 1300 735 20 SCOTT 3000 736 20 FORD 3000 737 20 JONES 2975 738 20 ADAMS 1100 739 20 SMITH 800 740 30 BLAKE 2850 741 30 ALLEN 1600 742 30 TURNER 1500 743 30 WARD 1250 744 30 MARTIN 1250 745 30 JAMES 950
