1. The object name in the database, with the naming rules of orle, all uppercase characters and underscores such as:
Customer_data2. Be careful to keep the word. 3. Keep the field name and type of consistency must ensure consistency when named the field and specify the data type. If the field is called "agreement_number" in a table, you don't change the name to "REF1" in another table. If the data type is an integer in a table, you can turn it in another table. Remember, you have done your own lives, others have to use your database. 4. Carefully select the digital type in SMALLINT and Tinyint types to be particularly careful, for example, if you want to see the total monthly sales, your total field type is Smallint, then if the total amount exceeds $ 32,767 You can't make a calculation. 5. Deleting tags contains a "Delete Tag" field in the table, so you can mark the row as delete. Do not delete a row separately in the relational database; it is best to use clear data programs and carefully maintain index integral. 6. Avoiding using trigger triggers can usually be implemented in other ways. The trigger may become interference when debugging the program. If you really need a trigger, you'd better focus on its documentation. 7. Contains version mechanisms It is recommended that you introduce version control mechanisms in the database to determine the version of the database in use. This requires this requirement anyway. For a long time, the needs of users will always change. It may eventually be required to modify the database structure. Although you can determine the version of the database structure by checking new fields or claims, I found that the version information is not more convenient in the database? . 8. Give text fields, pay the balance ID type text field, such as customer ID or order number, etc. should be set more than general imagination, because time is not long, you will be embarrassed because you want to add extra characters. For example, suppose your customer ID is 10 digits. Then you should set the length of the database table field to 12 or 13 characters. Is this a waste of space? There is a little, but there is so much that you imagine: A field extends 3 characters in 1 million records, plus a little index, but the entire database is more than 3MB of space. But this additional space can achieve the growth of database size without the need to refactor the entire database in the future. The number of ID cards from 15 is 18 bits is the best and most painful example. 9. Column [Field] Naming Tips We found that if you use a unified prefix, you will be greatly simplified when writing SQL expressions. This does have something disadvantage, such as destroying the role of the automatic table connection tool, the latter links the public column [field], but even if these tools are sometimes not connected. For a simple example, assume that there are two tables: Customer and Order. The prefix of the Customer table is CU_, so the subparaminated in the table is as follows: Cu_name_ID, Cu_Initials, and Cu_Address, etc. The prefix of the ORDER table is OR_, so the subparade name is: or_order_id, or_cust_name_id, or_quantity, and or_description, etc.
