Today, doing a batch job to run, we need to put in the oracle function in multiple rows of data are combined into one line, take the opportunity to play under several commonly used methods.
A, wm_concat
wm_concat function is a commonly used function is the oracle, functions: row transfer column, the column values from the query multiple rows may be used in a comma separated splicing, it becomes a data .
Example, there is now a risk table, each risk item (risk_id) corresponds to a number of rules (risk_rule), and now I have to follow the corresponding risk entry rules out inquiry.
select
risk_id, wm_concat(risk_rule)
from risk_jour
where risk_id='50010'
group by risk_id
NOTE: wm_concat function is a function oracle, mysql no function corresponding to mysql GROUP_CONCAT () function.
Two, listagg
After oracle11g listagg function is added is to achieve a built-in function string polymerization. Row column switch may also be implemented function, the multiple rows of data are combined into a certain field.
select
listagg(ri.risk_name, ';') within group(order by ri.risk_name)
as name_list
from t_risk ri
Instructions:
- LISTAGG ( 'splice required data field in the table', 'separator') WITHIN GROUP (ORDER BY 'before, the data required splicing table fields')
- Similarly Usage aggregate functions, through Group by statements to one field of each Group, spliced together.
