SQLiteStatement.java revision d24b8183b93e781080b2c16c487e60d51c12da31 
1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.database.sqlite;
18
19import android.os.SystemClock;
20
21/**
22 * A pre-compiled statement against a {@link SQLiteDatabase} that can be reused.
23 * The statement cannot return multiple rows, but 1x1 result sets are allowed.
24 * Don't use SQLiteStatement constructor directly, please use
25 * {@link SQLiteDatabase#compileStatement(String)}
26 */
27public class SQLiteStatement extends SQLiteProgram
28{
29    /**
30     * Don't use SQLiteStatement constructor directly, please use
31     * {@link SQLiteDatabase#compileStatement(String)}
32     * @param db
33     * @param sql
34     */
35    /* package */ SQLiteStatement(SQLiteDatabase db, String sql) {
36        super(db, sql);
37    }
38
39    /**
40     * Execute this SQL statement, if it is not a query. For example,
41     * CREATE TABLE, DELTE, INSERT, etc.
42     *
43     * @throws android.database.SQLException If the SQL string is invalid for
44     *         some reason
45     */
46    public void execute() {
47        mDatabase.lock();
48        boolean logStats = mDatabase.mLogStats;
49        long startTime = logStats ? SystemClock.elapsedRealtime() : 0;
50
51        acquireReference();
52        try {
53            native_execute();
54            if (logStats) {
55                mDatabase.logTimeStat(false /* write */, startTime, SystemClock.elapsedRealtime());
56            }
57        } finally {
58            releaseReference();
59            mDatabase.unlock();
60        }
61    }
62
63    /**
64     * Execute this SQL statement and return the ID of the most
65     * recently inserted row.  The SQL statement should probably be an
66     * INSERT for this to be a useful call.
67     *
68     * @return the row ID of the last row inserted.
69     *
70     * @throws android.database.SQLException If the SQL string is invalid for
71     *         some reason
72     */
73    public long executeInsert() {
74        mDatabase.lock();
75        boolean logStats = mDatabase.mLogStats;
76        long startTime = logStats ? SystemClock.elapsedRealtime() : 0;
77
78        acquireReference();
79        try {
80            native_execute();
81            if (logStats) {
82                mDatabase.logTimeStat(false /* write */, startTime, SystemClock.elapsedRealtime());
83            }
84            return mDatabase.lastInsertRow();
85        } finally {
86            releaseReference();
87            mDatabase.unlock();
88        }
89    }
90
91    /**
92     * Execute a statement that returns a 1 by 1 table with a numeric value.
93     * For example, SELECT COUNT(*) FROM table;
94     *
95     * @return The result of the query.
96     *
97     * @throws android.database.sqlite.SQLiteDoneException if the query returns zero rows
98     */
99    public long simpleQueryForLong() {
100        mDatabase.lock();
101        boolean logStats = mDatabase.mLogStats;
102        long startTime = logStats ? SystemClock.elapsedRealtime() : 0;
103
104        acquireReference();
105        try {
106            long retValue = native_1x1_long();
107            if (logStats) {
108                mDatabase.logTimeStat(false /* write */, startTime, SystemClock.elapsedRealtime());
109            }
110            return retValue;
111        } finally {
112            releaseReference();
113            mDatabase.unlock();
114        }
115    }
116
117    /**
118     * Execute a statement that returns a 1 by 1 table with a text value.
119     * For example, SELECT COUNT(*) FROM table;
120     *
121     * @return The result of the query.
122     *
123     * @throws android.database.sqlite.SQLiteDoneException if the query returns zero rows
124     */
125    public String simpleQueryForString() {
126        mDatabase.lock();
127        boolean logStats = mDatabase.mLogStats;
128        long startTime = logStats ? SystemClock.elapsedRealtime() : 0;
129
130        acquireReference();
131        try {
132            String retValue = native_1x1_string();
133            if (logStats) {
134                mDatabase.logTimeStat(false /* write */, startTime, SystemClock.elapsedRealtime());
135            }
136            return retValue;
137        } finally {
138            releaseReference();
139            mDatabase.unlock();
140        }
141    }
142
143    private final native void native_execute();
144    private final native long native_1x1_long();
145    private final native String native_1x1_string();
146}
147