Requirement to update a column by using Regular Expression

Question

Hi All,
    I have a requirement to update a column which is having values like below code.
based on the conditinos I need to update from ‘E’ to ‘Z’.  Few positions I need to update and remaining positions I need leave as it is.
How I can achive this requirement by using regular expression regexp_replace.
Actual value --> 'AEAAAEAA    EE    AA    EE    AA    EE    EEEAA    AA    AA       '
After update -->  'AZAAAZAA    EE    AA    EE    AA    EE    EEEAA    AA    AA       '

Answer 1

below is my requirement. I am adding the conditions dynamically as per the conditions. I dont know the position of the E. If 'E' is in any position I need to update with 'Z' if that 'E' satisfy the condition.
I dont want to update all the E's to Z's.
I want to update specific E's which satisfy the condition.
    IF l_kwhhilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,1,1) = ''E'' OR ';
        l_exp := l_exp||'Z';
    ELSE
        l_exp := l_exp||'\1';
    END IF;
    IF l_kwhilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,2,1) = ''E'' OR ';
         l_exp := l_exp||'Z';
    ELSE
        l_exp := l_exp||'\2';
    END IF;
    IF l_kvahilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,3,1) = ''E'' OR ';
         l_exp := l_exp||'Z';
    ELSE
        l_exp := l_exp||'\3';
    END IF;
    IF l_kvarhilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,4,1) = ''E'' OR ';
         l_exp := l_exp||'Z';
    ELSE
        l_exp := l_exp||'\4';
    END IF;
    IF l_todkwh1hilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,5,1) = ''E'' OR ';
         l_exp := l_exp||'Z';
    ELSE
        l_exp := l_exp||'\5';
    END IF;
    IF l_todkwh2hilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,6,1) = ''E'' OR ';
         l_exp := l_exp||'Z';
    ELSE
        l_exp := l_exp||'\6';
    END IF;
    l_exp := ''''||l_exp||'''';
    l_exp1 := '\1\2\3\4'||l_exp1;
    IF l_todkw1hilow >= 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,11,1) = ''E'' OR ';
         l_exp1 := l_exp1||'Z';
    ELSE
        l_exp1 := l_exp1||'\5';
    END IF;
    IF l_todkw2hilow = 1 THEN
        l_where := l_where||' SUBSTR(OVERRIDEFIELD,12,1) = ''E'' OR ';
         l_exp1 := l_exp1||'Z';
    ELSE
        l_exp1 := l_exp1||'\6';
    END IF;
    l_exp1 := ''''||l_exp1||'''';
IF i give 10 in the regexp_replace it is not working.
SET OVERRIDEFIELD =     REGEXP_REPLACE(SUBSTR(overridefield,1,6), ''(.)(.)(.)(.)(.)(.)'','||l_exp||')'||
                                          ' ||REGEXP_REPLACE(SUBSTR(overridefield,7,6), ''(.)(.)(.)(.)(.)(.)'','||l_exp1||')'||
                                          ' ||SUBSTR(overridefield,13)'||