case語句在select中的用法，以及，insert和select和case合用的例子

 

 

  SQL> select tag_name,tp_name,value from ins_dynamic; TAG_NAME     TP_NAME     VALUE ---------------- --------------- -------------- a                    NoString       1 b                    NoString       2

 

 

 

 

 

SQL> select (case when value='1' then 'value=1' when value='2' then 'value=2' else 'other value' end) tag_name1 from ins_dynamic;

 

 

TAG_NAME1

--------------------

value=1

value=2

 

 

 

 

SQL> insert into ins_dynamic(tag_name,tp_name) select 'zzzz.'||tag_name,(case when value='1' then 'value=1' when value='2' then 'value=2' else 'other value' end) from ins_dynamic;

 

已建立2行。 SQL> select tag_name,tp_name,value from ins_dynamic; TAG_NAME     TP_NAME     VALUE ---------------- --------------- -------------- a                    NoString       1 b                    NoString       2 zzz.a              value=1        NoString zzz.b              value=2        NoString 最後寫一個生猛的 DELETE FROM dict_column_info; INSERT INTO dict_column_info(table_name,column_name,data_type,data_length,is_nullable,is_key)  SELECT t1.table_name,t1.column_name, (case when t1.data_type='VARCHAR2' then 1        when t1.data_type='DATE' then 2        when t1.data_type='NUMBER' AND t1.data_precision=22 AND t1.data_scale=6 then 3        when t1.data_type='NUMBER' AND t1.data_precision=10 AND t1.data_scale=0 then 4        else 0 end), (case when t1.data_type='VARCHAR2' then t1.data_length        when t1.data_type='DATE' then 4        when t1.data_type='NUMBER' AND t1.data_precision=22 AND t1.data_scale=6 then 4        when t1.data_type='NUMBER' AND t1.data_precision=10 AND t1.data_scale=0 then 4        else 0 end), (case when t1.nullable='Y' then 1        when t1.nullable='N' then 0        else -1 end),  (case when (t1.table_name,t1.column_name) IN (SELECT t2.table_name,t2.column_name FROM all_cons_columns t2 where t2.owner = 'ISCS' AND t2.constraint_name IN (SELECT t3.constraint_name FROM all_constraints t3 where t3.owner = 'ISCS' AND t3.constraint_type = 'P')) then 1       else 0 end) from user_tab_columns t1;