src/com/android/providers/contacts/database/MoreDatabaseUtils.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License
 */

package com.android.providers.contacts.database;

/**
 * Static methods for database operations.
 */
public class MoreDatabaseUtils {

    /**
     * Builds a CREATE INDEX ddl statement for a given table and field.
     *
     * @param table The table name.
     * @param field The field to index.
     * @return The create index sql statement.
     */
    public static String buildCreateIndexSql(String table, String field) {
        return "CREATE INDEX " + buildIndexName(table, field) + " ON " + table
                + "(" + field + ")";
    }

    /**
     * Builds a DROP INDEX ddl statement for a given table and field.
     *
     * @param table The table name that was originally used to create the index.
     * @param field The field that was originally used to create the index.
     * @return The drop index sql statement.
     */
    public static String buildDropIndexSql(String table, String field) {
        return "DROP INDEX IF EXISTS " + buildIndexName(table, field);
    }

    /**
     * The index is created with a name using the following convention:
     * <p>
     * [table name]_[field name]_index
     */
    public static String buildIndexName(String table, String field) {
        return table + "_" + field + "_index";
    }

    /**
     * Build a bind arg where clause.
     * <p>
     * e.g. Calling this method with value of 4 results in:
     * <p>
     * "?,?,?,?"
     *
     * @param numArgs The number of arguments.
     * @return A string that can be used for bind args in a sql where clause.
     */
    public static String buildBindArgString(int numArgs) {
        final StringBuilder sb = new StringBuilder();
        String delimiter = "";
        for (int i = 0; i < numArgs; i++) {
            sb.append(delimiter).append("?");
            delimiter = ",";
        }
        return sb.toString();
    }
}