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PB9写的一个拆解SQL语句的通用函数

栏目:sybase时间:2014-02-01 11:17:40
将以下内容复制,另存为f_split_sql.srf 然后导入pbl中
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$PBExportHeader$f_split_sql.srf 
$PBExportComments$SQL操作:分割SQL语句为select、from、where、group by、order by 5个子句 
global type f_split_sql from function_object 
end type 
 
forward prototypes 
global subroutine replace_n (ref string input_str,readonly string replaced_str,readonly string replace_str) 
global subroutine f_split_sql (string as_sql, ref string as_select, ref string as_from, ref string as_where, ref string as_group, ref string as_order) 
end prototypes 
 
global subroutine replace_n (ref string input_str,readonly string replaced_str,readonly string replace_str);string s1 
string s2 
long p 
long n 
 
p = 1 
 
do while 1 = 1 
    p = pos(input_str,replaced_str,p) 
 
    if p = 0 then 
        exit 
    end if 
 
    s1 = mid(input_str,1,p - 1) 
    s2 = mid(input_str,p + len(replaced_str)) 
    input_str = s1 + replace_str + s2 
    p = p + len(replace_str) 
loop 
end subroutine 
 
global subroutine f_split_sql (string as_sql, ref string as_select, ref string as_from, ref string as_where, ref string as_group, ref string as_order);//==================================================================== 
// 过程(函数|Function): f_split_sql() 
//-------------------------------------------------------------------- 
// 描述(Description): 拆解SQL语句 
//-------------------------------------------------------------------- 
// 变量(Arguments):  
//              string  as_sql      传入的SQL语句(如:select a from t where b = 1 group by c order by c) 
//      ref     string  as_select   拆解后的select语句(如:select a) 
//      ref     string  as_from     拆解后的from  语句(如:from t) 
//      ref     string  as_where    拆解后的where 语句(如:where b = 1)  
//      ref     string  as_group    拆解后的group 语句(如:group by c)   
//      ref     string  as_order    拆解后的order 语句(如:order by c)   
//-------------------------------------------------------------------- 
// 返回(Returns):  (none) 
//-------------------------------------------------------------------- 
// 作者(Author):  yyoinge     Date: 2012-02-17 13:26 
//-------------------------------------------------------------------- 
// 修改历史(Modify History):  
//   
//-------------------------------------------------------------------- 
as_sql = lower(trim(as_sql)) 
if as_sql = '' then return 
as_select = ''; as_from = ''; as_group = ''; as_order = '' 
 
replace_n(as_sql,'~r',' ')  
replace_n(as_sql,'~n',' ')  
replace_n(as_sql,'~r~n',' ')  
replace_n(as_sql,'~t',' ')  
replace_n(as_sql, '(select ',' ( select ') 
replace_n(as_sql, ',select ',' , select ') 
replace_n(as_sql,';','  ')  
if leftw(as_sql, 7) <> 'select ' then return 
long ll_gb_p, ll_ob_p, ll_fr_p, ll_se_p, ll_wh_p, ll_tmp, ll_yh_p 
int li_leap = 0 
//先剔除''内的内容,如:'abc'替换为@@@@@ 
string ls_sql 
ls_sql = as_sql 
do while true 
    ll_yh_p = posw(ls_sql, "'")  
    if ll_yh_p <= 0 then exit 
    ll_tmp = posw(ls_sql, "'", ll_yh_p + 1) 
    if ll_tmp <= 0 then return 
    ls_sql = leftw(ls_sql, ll_yh_p - 1) + fill('@', ll_tmp - ll_yh_p + 1) + midw(ls_sql, ll_tmp + 1)     
loop 
 
//********************************  select 
ll_tmp = 8 
li_leap = -1 
do while true 
    ll_fr_p = posw(ls_sql, " from ", ll_tmp) 
    ll_se_p = posw(ls_sql, " select ", ll_tmp) 
    if ll_fr_p <= 0 then return 
    if ll_fr_p < ll_se_p or ll_se_p = 0 then 
        li_leap ++ 
    else 
        li_leap -- 
    end if 
    if li_leap = 0 then 
        as_select = leftw(as_sql, ll_fr_p) 
        exit 
    end if 
    if ll_fr_p <= 0 then ll_fr_p = 999999 
    if ll_se_p <= 0 then ll_se_p = 999999 
    ll_tmp = min(ll_fr_p, ll_se_p) + 5 
loop 
 
if as_select = '' then return 
 
 
//********************************  group by 
ll_gb_p = lastpos(ls_sql, " group by ") 
ll_ob_p = lastpos(ls_sql, " order by ") 
if ll_gb_p > 0 then 
    if posw(ls_sql, " from ", ll_gb_p + 1) > 0 or posw(ls_sql, " where ", ll_gb_p + 1) > 0 then 
        as_group = '' 
        ll_gb_p = 0 
    else 
        if ll_ob_p > ll_gb_p then 
            as_group = midw(as_sql, ll_gb_p, ll_ob_p - ll_gb_p) 
        else 
            as_group = midw(as_sql, ll_gb_p) 
        end if 
    end if 
else 
    as_group = '' 
end if 
 
//********************************  order by 
if ll_ob_p > 0 then 
    if posw(ls_sql, " from ", ll_ob_p + 1) > 0 or posw(ls_sql, " where ", ll_ob_p + 1) > 0 then 
        as_order = '' 
        ll_ob_p = 0 
    else 
        as_order = midw(as_sql, ll_ob_p) 
    end if 
else 
    as_order = '' 
end if 
//取得select from where 语句的最后一个字符的位置+1 
if ll_gb_p <= 0 then ll_gb_p = ll_ob_p 
if ll_gb_p <= 0 then ll_gb_p = lenw(as_sql) + 1 
 
//********************************  where 
as_sql = midw(leftw(as_sql,ll_gb_p - 1), ll_fr_p) 
ls_sql = midw(leftw(ls_sql,ll_gb_p - 1), ll_fr_p) 
ll_wh_p = lastpos(ls_sql, " where ") 
if ll_wh_p <= 0 then 
    as_where = '' 
else 
    ll_tmp = 5 
    li_leap = 0 
    do while true 
        ll_se_p = posw(ls_sql, "(", ll_tmp) 
        ll_fr_p = posw(ls_sql, ")", ll_tmp) 
        if ll_se_p > ll_wh_p then ll_se_p = 0 
        if ll_fr_p > ll_wh_p then ll_fr_p = 0 
        if (ll_se_p = 0 and ll_fr_p = 0) then exit 
        if ll_fr_p < ll_se_p or ll_se_p = 0 then 
            li_leap ++ 
        else 
            li_leap -- 
        end if 
        if ll_fr_p <= 0 then ll_fr_p = 999999 
        if ll_se_p <= 0 then ll_se_p = 999999 
        ll_tmp = min(ll_fr_p, ll_se_p) + 1 
    loop 
    if li_leap <> 0 then 
        as_where = '' 
    else 
        as_where = midw(as_sql, ll_wh_p) 
        as_sql = leftw(as_sql, ll_wh_p) 
    end if 
end if 
 
//********************************  from 
as_from = as_sql 
 
end subroutine 
 
调用时,5自学网,这样写:
[cpp] view plaincopy
string ls_sql, ls_select, ls_from, ls_where, ls_group, ls_order 
 
ls_sql = dw_1.getsqlselect() 
 
f_split_sql(ls_sql, ls_select, ls_from, ls_where, ls_group, ls_order) 
 
 
即可将SQL语句ls_sql ,拆解为5个部分,之后就可以对各个部分进行添加、修改,然后重新组成新的SQL语句了

作者 yyoinge的专栏 ,5自学网
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