This is sample of query for SQL insert query validation constraints to limit number of records lets you want to insert only 1000 records in table .
We can restrict number of rows, but need to add a column on which we can add some constraint ... check below example.!
CREATE TABLE TAB_1000_ROWS
AS SELECT ROWNUM COL1 FROM DUAL CONNECT BY ROWNUM <1001;
ALTER TABLE TAB_1000_ROWS
ADD CONSTRAINT CHECK_CONST CHECK (COL1 BETWEEN 1 AND 1000);
ALTER TABLE TAB_1000_ROWS
MODIFY COL1 NUMBER NOT NULL;
ALTER TABLE TAB_1000_ROWS
ADD CONSTRAINT UNIQUE_COL1 UNIQUE (COL1); -- or we can also use sequence with max as 100 and no-cycle!
after insertion of 100 values it wont allow any new values to get inserted! will throw check or unique constraint!