1.寤烘祴璇曟暟鎹傚緩琛╰est_tbl(鍚瓧絎︿覆綾誨瀷鐨勫瓧孌礳ontent),鎻掑叆10W鏉¤褰曘?/strong>
--寤鴻〃
create table test_tbl (id number,content varchar2(1000))錛?br /> --鎻掑叆10W鏉℃祴璇曡褰?/span>
begin
dbms_random.seed(12345678);
for i in 1 .. 100000
loop
insert into test_tbl values(i, dbms_random.string('L',dbms_random.value(10,1000)));
end loop;
commit;
end;
2.鍒涘緩鑷畾涔夊嚱鏁頒竴錛堥噰鐢ㄥ驚鐜埅瀛愪覆鐨勬柟寮忓疄鐜幫紝濡傛灉鎴埌鐨勫瓙涓茬瓑浜庣洰鏍囧瓙涓插垯鍑虹幇嬈℃暟鍔?銆傦級(jí)
create or replace function f1(str_pattern in varchar2,str_mother in varchar2)
return number
is
i number := 1;
cnt number := 0;
len_pattern number := length(str_pattern);
len_mother number := length(str_mother);
begin
while(i <= len_mother)
loop
if(substr(str_mother, i ,len_pattern) = str_pattern) then
cnt := cnt + 1;
i := i+ len_pattern;
else
i := i+1;
end if;
end loop;
return cnt;
end;
3.鍒涘緩鑷畾涔夊嚱鏁頒簩(寰幆浣跨敤Instr鍑芥暟鍒╃敤occurrence鍙傛暟瀹炵幇錛屽驚鐜竴嬈ntr鍑芥暟寰楀埌涓涓綅緗畃os鍊鹼紝騫惰occurrence鍔?銆傚鏋減os鍊間笉涓洪浂錛岃〃紺虹洰鏍囧瓙涓茬occurrence嬈″湪姣嶄覆涓瓨鍦紱鍙嶄箣琛ㄧず鍐嶄篃涓嶅瓨鍦ㄤ簡錛屼簬鏄鍑哄驚鐜傛渶鍚巓ccurrence-1鍗充負(fù)鎵寰?
Intr鍑芥暟璇存槑錛欼nstr(string, substring, position, occurrence) 鍏朵腑
string錛氫唬琛ㄦ簮瀛楃涓詫紱
substring錛氫唬琛ㄦ兂鑱簮瀛楃涓蹭腑鏌ユ壘鐨勫瓙涓詫紱
position錛氫唬琛ㄦ煡鎵劇殑寮濮嬩綅緗紝璇ュ弬鏁板彲閫夌殑錛岄粯璁や負(fù) 1錛?br /> occurrence錛氫唬琛ㄦ兂浠庢簮瀛楃涓煡鎵懼嚭絎嚑嬈″嚭鐜扮殑substring錛岃鍙傛暟涔熸槸鍙夌殑錛岄粯璁や負(fù)1錛?br /> 榪斿洖鍊間負(fù)錛氭煡鎵懼埌鐨勫瓧絎︿覆鐨勪綅緗?/span>
create or replace function f2(str_pattern in varchar2,str_mother in varchar2)
return number
is
pos number;
occurrence number := 1;
begin
loop
pos := instr(str_mother,str_pattern,1, occurrence);
exit when pos = 0;
occurrence := occurrence + 1;
end loop;
return occurrence - 1;
end;
3.嫻嬭瘯鏁堢巼 select count(*) from test_tbl where f1('abc',content) > 1
--鐢ㄦ椂59.223 S
select count(*) from test_tbl where f2('abc',content) > 1
--鐢ㄦ椂2.016 S
select count(*) from test_tbl where f1('a',content) > 10
--鐢ㄦ椂59.453 S
select count(*) from test_tbl where f2('a',content) > 10
--鐢ㄦ椂8.36 S
4.鎬葷粨錛氬緢濂界殑鍒╃敤鍐呯疆鍑芥暟錛岀瀛︾殑鎶婂唴緗嚱鏁版斁鍒板悎鐞嗙殑浣嶇疆鑳藉緢濂界殑鎻愰珮鏁堢巼
5.鍚庤
瀵逛簬璇ユ渚嬶紝濡傛灉鐩爣瀛愪覆鍚湁澶氫釜瀛楃鐢?span style="color: #0000ff">f2鏁堢巼杈冮珮錛屽鏋滅洰鏍囧瓙涓叉墍鍚瓧絎﹀緢灝戞瘮濡傚氨涓涓瓧絎?寤鴻鐢ㄧ畝渚垮姙娉曪細(xì)1.鍦ㄦ瘝瀛楃涓蹭腑鎶婃湪鐩爣瀛椾覆鏇挎崲涓虹┖('')寰楀埌鏂板瓧絎︿覆銆?.鍒╃敤 (姣嶄覆闀垮害-鏂頒覆闀垮害)/鐩爣瀛愪覆闀垮害 寰楀埌鐨勫氨鏄瓙涓茬殑鍑虹幇嬈℃暟銆?/span>
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