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¹Ø¼ü×Ö: oracle cast() º¯ÊýÎÊÌâ
SQL> create table t1(a varchar(10));
Table created.
SQL> insert into t1 values ('12.3456');
1 row created.
SQL> select round(a) from t1;
  ROUND(A)
----------
        12
SQL> select round(a,3) from t1;
ROUND(A,3)
----------
    12.346
SQL> select cast(a as int) from t1;
CAST(AASINT)
------------
          12
SQL> select cast(a as number(8,4)) from t1;
CAST(AASNUMBER(8,4))
--------------------
             12.3456
=========================================================
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SQL> select round(12.45) round,trunc(12.45) trunc,ceil(12.45) ceil
  2  from dual
  3  /
     ROUND      TRUNC       CEIL
---------- ---------- ----------
        12         12         13
SQL> select round(12.54) round,trunc(12.54) trnc,ceil(12.54) ceil
  2  from dual
  3  /
     ROUND       TRNC       CEIL
---------- ---------- ----------
        13         12         13
SQL>