[SQL] can any one solve this problem

[Penchalaiah P.]

emp_table( Cdacno varchar (7) (primary key), Personal_No varchar (10)(foreign key), Name varchar (40));   personal_table ( Personal_No varchar (10) (primary key), Cdacno varchar (7), Date_Of_Birth date);   unit_master ( Unit id varchar (10) (primary key), Unit_Name varchar(25), Unit_Location varchar(25));   Unit_Details_table (  Unit_id varchar (foreign key) CDA_No varchar(7) foreign key);   rank_table( Rank_ID numeric(2)(primary key), Rank_Code numeric(2), Rank_Name varchar (25));   Rank_Date_table (   Rank_Date__ID numeric NOT NULL,   CDA_No varchar(7) (foreign key),   Rank_ID numeric(2));   My query is ….if I give cdacno I have to get per_no from personal_table.. With this I have to display rank_name from rank_table ,name from emp_table, unit_name from unit_master..   Like that if I give per_no I have to get cdacno from emp_table.. .. With this I have to display rank_name from rank_table ,name from emp_table, unit_name from unit_master..   And here unit_name is depends on unit_details_table ..and rank_name is depends on rank_date_table..   Doing these things first it has to check when we r giving cdacno.. whether  per_no is null or not.. like this if I give per_no it has to check cdacno is null or not.   Let me know the solution.. But I written one function to this to get per_no if I give cdacno………………….     Thanks  &  Regards Penchal reddy | Software Engineer            Infinite Computer Solutions | Exciting Times…Infinite Possibilities... SEI-CMMI level 5 | ISO 9001:2000 IT SERVICES | BPO                                                                                                                                                                           Telecom | Finance | Healthcare | Manufacturing | Energy & Utilities | Retail & Distribution | Government                                                        Tel +91-80-5193-0000(Ext:503)| Fax  +91-80-51930009 | Cell No  +91-9980012376|www.infics.com           Information transmitted by this e-mail is proprietary to Infinite Computer Solutions and/ or its Customers and is intended for use only by the individual or entity to which it is addressed, and may contain information that is privileged, confidential or exempt from disclosure under applicable law. If you are not the intended recipient or it appears that this mail has been forwarded to you without proper authority, you are notified that any use or dissemination of this information in any manner is strictly prohibited. In such cases, please notify us immediately at [EMAIL PROTECTED] and delete this mail from your records.   Information transmitted by this e-mail is proprietary to Infinite Computer Solutions and / or its Customers and is intended for use only by the individual or the entity to which it is addressed, and may contain information that is privileged, confidential or exempt from disclosure under applicable law. If you are not the intended recipient or it appears that this mail has been forwarded to you without proper authority, you are notified that any use or dissemination of this information in any manner is strictly prohibited. In such cases, please notify us immediately at [EMAIL PROTECTED] and delete this email from your records.