Doubt in Internal table

HI All

I need fetch all matnr ,ersda,ernam and mtart from table MARA,Iam using as follows but iam getting only one records.please i need all records from mara as my requirement.

DATA: BEGIN OF wa_MARA,

MATNR TYPE MARA-MATNR,

ERSDA TYPE MARA-ERSDA,

ERNAM TYPE MARA-ERNAM,

MTART TYPE MARA-MTART,

END OF wa_mara.

DATA:it_MARA LIKE TABLE OF wa_MARA WITH HEADER LINE.

select MATNR ERSDA ERNAM MTART from MARA into table it_mara.

please help me.

Thanks.

jay