Hi Gurudutt,
Multiple options:
1) For each table, you can open the definition and there is GENERATE script option on the right hand side top corner. But you will have to repeat the procedure for all the tables.
2) You can use EXPORT and IMPORT of HANA tables facility and can move the tables from one system to another (if that is your objective to create DDLs).
3) You can refer to the thread http://scn.sap.com/thread/3291461, in which Lars has wrote a wonderful piece of code for ALTER TABLE script. You can modify the code and generate CREATE TABLE script for your 150 tables.
Regards,
Ravi