check whether the data is already exist in table, or to check table is empty
friends, I need help in sqlite query for check whether the data is already exist in table, or to check table is empty or not,let's give queries for it.
Thanks in advance.
SELECT COUNT(*) FROM `tableName`;
如果结果为0，表格为空;）
REFINED QUERY
SELECT COUNT(*) FROM TABLE WHERE ROWNUM=1
另请请阅读关于DatabaseUtils。
/**
* checks database if a column has a value in the table
*
* @param db
* @param tableName
* @param column
* @param value
* @param rowid to check against and skip if necessary
* @return boolean
*/
public static boolean ExistsWithName(SQLiteDatabase db, String tableName, String column,
String value, Long rowid) {
String sql = String.format("select 1 from %s where %s = '%s'", tableName, column, value);
if (rowid != null) {
sql += " and _id != " + rowid;
}
Cursor c = null;
Boolean ret = false;
try {
c = db.rawQuery(sql, null);
if (c != null) {
if (c.moveToFirst()) {
ret = (c.getCount() > 0);
} else {
ret = false;
}
}
} catch (Exception e) {
Log.v(tableName, e.getMessage(), e);
e.printStackTrace();
} finally {
if (c != null)
c.close();
}
return ret;
}