In Oracle, the built-in package DBMS_RANDOM is useful for generating random test data. The following example shows you how to generate large volumes of test records quickly by combining it into a query.
CREATE TABLE TestTable (
id NUMBER,
number_col NUMBER(5),
string_col VARCHAR2(50),
created_date DATE,
CONSTRAINT TestTable_pk PRIMARY KEY (id)
);
INSERT /*+ APPEND */ INTO TestTable
SELECT level AS id,
TRUNC(DBMS_RANDOM.value(1,5)) AS number_col,
DBMS_RANDOM.string('L',TRUNC(DBMS_RANDOM.value(10,50))) AS string_col,
TRUNC(SYSDATE + DBMS_RANDOM.value(0,366)) AS created_date
FROM dual
CONNECT BY level <= 10000;
COMMIT;
The above INSERT statement will generate 10000 rows of random data, if you want more rows, just change 10000 to the number you want it to be.