选择返回时没有oracle select into变量？

declare
 fName varchar2(255 char);
begin
 SELECT x.constraint_name into fName FROM all_constraints x
 JOIN all_cons_columns c ON
 c.table_name = x.table_name AND c.constraint_name = x.constraint_name
 WHERE x.table_name = 'MY_TABLE_NAME' AND x.constraint_type = 'R' AND c.column_name ='MY_COLUMN_NAME';
 if fName is not null THEN
  execute immediate 'alter table MY_TABLE_NAME drop constraint ' || fName;
 end if;

 SELECT x.constraint_name into fName FROM all_constraints x
 JOIN all_cons_columns c ON
 c.table_name = x.table_name AND c.constraint_name = x.constraint_name
 WHERE x.table_name = 'OTHER_MY_TABLE_NAME' AND x.constraint_type = 'R' AND c.column_name ='OTHER_MY_COLUMN_NAME';
 if fName is not null THEN
  execute immediate 'alter table OTHER_MY_TABLE_NAME drop constraint ' || fName;
 end if;
end;

嗨@,
我正在行使上面的代码来获取我想要删除的束缚的名称,而且我有许多这样的select into而不是if – >删除声明.
我的题目是,假如个中一个选择没有返回任何非常,则抛出非常.我可以捕捉非常,可是在“begin end”布局的末端(以是在全部select语句之后,以是别的的drop永久不会被执行).我怎么能布置这个,假如选择返回什么我只是不想丢掉任何对象:)

假若有另一种要领来界说一个变量并从select中添补它而不抛出非常,无论返回的名称是否为null,我都更喜好它:)(此刻我只是让这个选择事变,除了假如选择返回的环境:))

办理要领

declare
 fName varchar2(255 char);
begin
 begin
   SELECT x.constraint_name into fName FROM all_constraints x
   JOIN all_cons_columns c ON
   c.table_name = x.table_name AND c.constraint_name = x.constraint_name
   WHERE x.table_name = 'MY_TABLE_NAME' AND x.constraint_type = 'R' AND c.column_name ='MY_COLUMN_NAME';
exception
  when no_data_found then
    fName := null;
end;

 if fName is not null THEN
  execute immediate 'alter table MY_TABLE_NAME drop constraint ' || fName;
 end if;

begin    
 SELECT x.constraint_name into fName FROM all_constraints x
 JOIN all_cons_columns c ON
 c.table_name = x.table_name AND c.constraint_name = x.constraint_name
 WHERE x.table_name = 'OTHER_MY_TABLE_NAME' AND x.constraint_type = 'R' AND c.column_name ='OTHER_MY_COLUMN_NAME';
exception
  when no_data_found then
    fName := null;
end;

 if fName is not null THEN
  execute immediate 'alter table OTHER_MY_TABLE_NAME drop constraint ' || fName;
 end if;
end;

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