SQL表添加约束以检查数量限制

Question

I am creating a table in oracle DB and trying to add constraint so that the numbers allowed in the column are 1,2,3.

CREATE TABLE "TABLE_EXAMPLE"
(
.
.
"PROTOCOL" NUMBER (1,2,3),

....)

CONSTRAINT "CH1"
        CHECK ("PROTOCOL" BETWEEN 1 AND 3),

Am I doing right or any better way?

Answer 1

CREATE TABLE TABLE_EXAMPLE 
(
 ...
  PROTOCOL NUMBER(1) NOT NULL CONSTRAINT CH1 CHECK (PROTOCOL IN (1,2,3))
 ...
);

BETWEEN 1 AND 3 includes 1.5, 1.6, etc.

And I'd recommend not to use quotes " unless you have special characters in table or column names...

Answer 2

If you are going to check in the table level Check Constraint is the best way. because if you are inserting larger value then the check constraint ll throw the error.