在Oracle中创建表之前是否存在检查表?

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尝试检查在Oracle中创建之前是否存在表

IF((SELECT count(*) FROM dba_tables where table_name = 'EMPLOYEE') <= 0)
THEN
create table EMPLOYEE
(
ID NUMBER(3),
NAME VARCHAR2(30) NOT NULL
)
END IF;

这给了我错误

Error: ORA-00900: invalid SQL statement
SQLState:  42000
ErrorCode: 900
Position: 1

我搜索条件的语法IF,我认为这也是写。请建议我....

提问于
用户回答回答于

declare
nCount NUMBER;
v_sql LONG;

begin
SELECT count(*) into nCount FROM dba_tables where table_name = 'EMPLOYEE';
IF(nCount <= 0)
THEN
v_sql:='
create table EMPLOYEE
(
ID NUMBER(3),
NAME VARCHAR2(30) NOT NULL
)';
execute immediate v_sql;

END IF;
end;

但我宁愿去捕捉异常,节省一些不必要的代码行:

declare
v_sql LONG;
begin

v_sql:='create table EMPLOYEE
  (
  ID NUMBER(3),
  NAME VARCHAR2(30) NOT NULL
  )';
execute immediate v_sql;

EXCEPTION
    WHEN OTHERS THEN
      IF SQLCODE = -955 THEN
        NULL; -- suppresses ORA-00955 exception
      ELSE
         RAISE;
      END IF;
END; 
/
用户回答回答于

请尝试:

SET SERVEROUTPUT ON
DECLARE
v_emp int:=0;
BEGIN
  SELECT count(*) into v_emp FROM dba_tables where table_name = 'EMPLOYEE'; 

  if v_emp<=0 then
     EXECUTE IMMEDIATE 'create table EMPLOYEE ( ID NUMBER(3), NAME VARCHAR2(30) NOT NULL)';
  end if;
END;

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