Android in-depth study of SQLite instances (III)

Written in front of, this article Reprinted from http://www.eoeandroid.com/thread-81912-1-1.html

// Query by page 2 Public cursor getdaterawperson (INT startresult, int maxresult) {// list persons = new arraylist (); sqlitedatabase database = dbmanger. getwritabledatabase (); // cursor is a cursor type. A cursor is actually a dataset in the database. // rawquery (string SQL, string [] S) parameter 1 is an SQL statement parameter 2 is the specific values stored in the condition placeholder in parameter 1 SQL statement. These values are a string array return database. rawquery ("select personid AS _ id, name, age from person limit ?,? ", New string [] {string. valueof (startresult), String. valueof (maxresult)});} // obtain the total number of records public long getcount () {sqlitedatabase database = dbmanger. getwritabledatabase (); // cursor is a cursor type. cursor is actually a data set in the database. cursor = database. rawquery ("select count (*) from person", null); If (cursor. movetolast () {return cursor. getlong (0) ;}return 0 ;}}

Entity operation class

Package EOE. demo; import Java. util. arraylist; import Java. util. list; import android. content. context; import android. database. cursor; import android. database. SQLite. sqlitedatabase; import android. util. log; import it. bean. person; /***** entity operation class * rawquery execution SQL query * execute addition, deletion, and modification SQL * The Inheritance class of sqliteopenhelper mangerdatabase obtains the database management instance * This management instance is obtained by the sqlitedatabase object * This object can execute rawquery and execsql Methods */public class personservic E {private mangerdatabase dbmanger; Public personservice (context) {dbmanger = new mangerdatabase (context) ;}// Save Public void save (person) {/*** open the getwritabledatabase () and getreadabledatabase () Methods of the database to obtain an sqlitedatabase instance used to operate the database. * However, the getwritabledatabase () method opens the database in read/write mode. Once the disk space of the database is full, the database can only read but cannot write. * If getwritabledatabase () is used () an error occurs. * The getreadabledatabase () method first opens the database in read/write mode. If the disk space of the database is full, the database fails to be opened. * If the opening fails, the database will continue to be opened in read-only mode. * Sqlitedatabase SQLite database management class */sqlitedatabase database = dbmanger.getwritabledatabase(registry.database.exe csql ("insert into person (name, age) values (?,?) ", New object [] {person. getname (), person. getage ()});} // update public void Update (person) {sqlitedatabase database = dbmanger. getwritabledatabase (); // execsqlis the execution of SQL statement database.exe csql ("Update person set name = ?, Age =? Where personid =? ", New object [] {person. getname (), person. getage (), person. getpersonid ()});} // query data by ID: public person findbyid (integer ID) {sqlitedatabase database = dbmanger. getwritabledatabase (); // cursor is a cursor type. cursor is actually a data set in the database. cursor = database. rawquery ("select * From person where personid =? ", New string [] {string. valueof (ID)}); If (cursor. movetonext () {log. I ("XXX", "XXX" + String. valueof (cursor. getint (3); person = new person (cursor. getint (0), cursor. getstring (1), cursor. getshort (2); Return person;} return NULL;} // Delete public void Delete (integer... IDS) {If (IDs. length> 0) {stringbuilder sb = new stringbuilder (); For (integer ID: IDS) {sb. append ('? '). Append (',');}