"Android Interview Treasure" study notes (sixth: database)

How do I copy the contents of table1 to table2?

CREATE TABLE Table2 as SELECT * FROM table1;

SQL statement to create a view?

Create view if not exists view1 as SELECT * FROM table1;

What are the return values of ABS (X) in several cases?
X is positive and 0: returns x;

X is negative: returns-X;

X is null and returns null;

Not numeric: returns 0;

Out of range: overflow error.

How do I get the number of record rows affected by the last SQL statement execution?

Select changes ();

What value does length (X) return in the following cases?

Blob: Returns the number of bytes in the binary data;

NULL: Returns NULL;

Numeric value: Converts numeric values to string processing.

The role of the like function:

SELECT * FROM table1 where like ('%bill% ', name)

Use of the NULLIF function:

When x and Y are not the same, the NULLIF function returns x, or null if the same is true.

substr function Usage:

Select substr (' ABCDEFG ', 2, 3)

How do I get the data type of the current field?

Select typeof (Field1) from table1;

Which date and time functions does SQLite support?
Date, Time, DateTime, Julianday, strftime

Select DateTime (' Now ');
Result: 2006-10-17 12:55:54

Select DateTime (' 2006-10-17 ');
Result: 2006-10-17 12:00:00

Select DateTime (' 2006-10-17 00:20:00 ', ' +1 hour ', ' -12 minute ');
Result: 2006-10-17 01:08:00

Select Date (' 2006-10-17 ', ' +1 Day ', ' +1 Year ');
Results: 2007-10-18

How do I output the current date and time?

Select Date (' Now ');

Select time (' Now ');

The arithmetic rules of the AVG (X) function?
X is null:null;

X is a string or blob: The convertible is converted to a numeric value, otherwise treated as 0;

All fields are null:null;

When do I call the Onupgrade method?

The database file exists and the current version number is higher than the version number when it was last created or promoted.

How do I publish a SQLite database with data with the APK program?
http://blog.csdn.net/zz_mm/article/details/7642127

What is a db4o database?
Database for objects, open source object-oriented databases

How do I save an object instance to the Db4o database?

Student Student = new Student (1, "Mike", 100);

Db.store (student);

Db.commit ();

How do I query, modify, and delete data through db4o?

Http://wenku.baidu.com/link?url=MTyzcHMgymzcBCQOzm3y8vqiVp0Rh-sEuzAtckXFwXKw8xaJ-lk-7WXdcIB5_ Hhlae0haklfdwgplfa0vrxfwuvckfwr5lelcdmisexr6t3

"Android Interview Treasure" study notes (sixth: database)