Traps that have been filled together in those years

20140508

1. SQL statement, splicing query, adding single quotation marks for the string type, using =, and directly assigning values for the integer type

// Method 1

String SQL = "select ID, name from table_temp where name = 'host' Limit 30 offset 20 ";

DB. rawquery (SQL, null );

// Method 2 can I say it is not verified?

String SQL = "select ID, name from table_temp where name =? Limit? Offset? "

DB. rawquery (SQL, new string [] {name_value, limit_value, offset_value });

2. fuzzy query, using like, % placeholder

Three methods of fuzzy search

// Method 1

String SQL = "select ID, name from table_temp where name like '%" + keyValue + "' % ";

DB. rawquery (SQL, null );

// Method 2 not verified

String SQL = "select ID, name from table_temp where name like? ";

DB. rawquery (SQL, new string [] {keyValue });

3. Obtain the data in the returned value of cursor.

Problems encountered in the code today

Android. database. cursorindexoutofboundsexception: Index-1 requested, with a size of 1

I always thought it was a column query problem.

Google discovered that the subscript returned by cursor by default is-1. Before the value is set, move the subscript to a place with a return value.

After adding cursor. movetofirst (), there is no problem.

Explanation and stackoverflow description

4. I have to say that there is another more important thing today, and it is planted again under break.

In the switch case, the break is missing;

Traps that have been filled together in those years