下列不是有效的Sqoop命令的是？ Asqoop import Bsqoop list-database Csqoop list-tables Dsqoop create-table

不是有效的Sqoop命令的是Dsqoop create-table。Sqoop命令可以用于在Hadoop集群和关系型数据库之间进行数据传输。Sqoop支持的命令包括import、export、list-databases、list-tables等。但是，Sqoop不提供create-table命令来创建表。

相关问题

编写一个程序(使用 Java 和 JDBC) ，该程序接收电脑本地的一个名为“University.db”的数据库并生成内容的文本“备份”），使用SQLite-jdbc-3.7.2驱动，包含所有的 INSERT. . INTO 语句，所有正确的 INSERT. . INTO 语句，在开始时包含 CREATETABLE 语句，这些语句创建文本文件将记录的表。(但是没有指示主键和外键)。在开始时包含 CREATETABLE 语句，这些语句创建文本文件将记录的表。（包含外键）还包括数据库中存在的索引的详细信息。添加代码以确定存在哪些索引，并在备份中包含 CREATEINDEX 语句以重新创建这些索引。存在外键的时候，获取表的信息时根据外键依赖关系对表进行排序

好的，为了完成你的要求，我们需要使用Java和JDBC编写一个程序。首先，我们需要下载SQLite-jdbc-3.7.2驱动并将其添加到我们的项目中。

然后我们可以开始编写代码。首先，我们需要连接到数据库并获取所有表的名称。

public class BackupDatabase {
    public static void main(String[] args) {
        String url = "jdbc:sqlite:/path/to/University.db";
        Connection conn = null;
        try {
            conn = DriverManager.getConnection(url);
            DatabaseMetaData metaData = conn.getMetaData();
            ResultSet tables = metaData.getTables(null, null, "%", null);
            while (tables.next()) {
                String tableName = tables.getString("TABLE_NAME");
                System.out.println("Backing up table: " + tableName);
                // backup the table
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }
    }
}

接下来，我们需要获取每个表的结构和数据。对于每个表，我们将生成一个包含 CREATE TABLE 和 INSERT INTO 语句的文本文件。

String sql = "SELECT * FROM " + tableName;
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();

ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();

// generate CREATE TABLE statement
StringBuilder createTableStatement = new StringBuilder();
createTableStatement.append("CREATE TABLE ").append(tableName).append(" (");
for (int i = 1; i <= columnCount; i++) {
    String columnName = metaData.getColumnName(i);
    String columnType = metaData.getColumnTypeName(i);
    createTableStatement.append(columnName).append(" ").append(columnType);
    if (i < columnCount) {
        createTableStatement.append(", ");
    }
}
createTableStatement.append(");");

// generate INSERT INTO statements
StringBuilder insertIntoStatements = new StringBuilder();
while (rs.next()) {
    StringBuilder values = new StringBuilder();
    values.append("(");
    for (int i = 1; i <= columnCount; i++) {
        Object value = rs.getObject(i);
        if (value != null) {
            values.append("'").append(value.toString()).append("'");
        } else {
            values.append("NULL");
        }
        if (i < columnCount) {
            values.append(", ");
        }
    }
    values.append(")");
    insertIntoStatements.append("INSERT INTO ").append(tableName).append(" VALUES ").append(values).append(";\n");
}

// write backup to file
String fileName = tableName + ".sql";
try (PrintWriter writer = new PrintWriter(fileName)) {
    writer.println(createTableStatement.toString());
    writer.println(insertIntoStatements.toString());
} catch (FileNotFoundException e) {
    e.printStackTrace();
}

现在，我们已经可以生成包含 CREATE TABLE 和 INSERT INTO 语句的文本文件了。但是，我们还需要添加外键和索引。

对于外键，我们可以使用以下代码获取外键依赖关系并对表进行排序。

// get foreign keys for table
ResultSet foreignKeys = metaData.getImportedKeys(null, null, tableName);

// sort tables based on foreign key dependencies
List<String> sortedTables = new ArrayList<>();
while (foreignKeys.next()) {
    String fkTableName = foreignKeys.getString("FKTABLE_NAME");
    if (!sortedTables.contains(fkTableName)) {
        sortedTables.add(fkTableName);
    }
}
sortedTables.add(tableName);

对于索引，我们可以使用以下代码获取索引信息并生成 CREATE INDEX 语句。

// get indexes for table
ResultSet indexes = metaData.getIndexInfo(null, null, tableName, false, false);

// generate CREATE INDEX statements
while (indexes.next()) {
    String indexName = indexes.getString("INDEX_NAME");
    if (indexName != null && !indexName.equals("sqlite_autoindex_" + tableName + "_1")) {
        String columnName = indexes.getString("COLUMN_NAME");
        String unique = indexes.getBoolean("NON_UNIQUE") ? "" : "UNIQUE ";
        String indexType = indexes.getBoolean("INDEXED_ASC") ? "ASC" : "DESC";
        String createIndexStatement = "CREATE " + unique + "INDEX " + indexName + " ON " + tableName + " (" + columnName + " " + indexType + ");";
        writer.println(createIndexStatement);
    }
}

现在我们已经可以生成包含 CREATE TABLE、INSERT INTO、CREATE INDEX 和外键的文本文件了。完整的代码如下：

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class BackupDatabase {
    public static void main(String[] args) {
        String url = "jdbc:sqlite:/path/to/University.db";
        Connection conn = null;
        try {
            conn = DriverManager.getConnection(url);
            DatabaseMetaData metaData = conn.getMetaData();
            ResultSet tables = metaData.getTables(null, null, "%", null);
            while (tables.next()) {
                String tableName = tables.getString("TABLE_NAME");
                System.out.println("Backing up table: " + tableName);

                // get foreign keys for table
                ResultSet foreignKeys = metaData.getImportedKeys(null, null, tableName);

                // sort tables based on foreign key dependencies
                List<String> sortedTables = new ArrayList<>();
                while (foreignKeys.next()) {
                    String fkTableName = foreignKeys.getString("FKTABLE_NAME");
                    if (!sortedTables.contains(fkTableName)) {
                        sortedTables.add(fkTableName);
                    }
                }
                sortedTables.add(tableName);

                // backup table
                String sql = "SELECT * FROM " + tableName;
                PreparedStatement pstmt = conn.prepareStatement(sql);
                ResultSet rs = pstmt.executeQuery();

                ResultSetMetaData metaData = rs.getMetaData();
                int columnCount = metaData.getColumnCount();

                // generate CREATE TABLE statement
                StringBuilder createTableStatement = new StringBuilder();
                createTableStatement.append("CREATE TABLE ").append(tableName).append(" (");
                for (int i = 1; i <= columnCount; i++) {
                    String columnName = metaData.getColumnName(i);
                    String columnType = metaData.getColumnTypeName(i);
                    createTableStatement.append(columnName).append(" ").append(columnType);
                    if (i < columnCount) {
                        createTableStatement.append(", ");
                    }
                }
                createTableStatement.append(");");

                // generate INSERT INTO statements
                StringBuilder insertIntoStatements = new StringBuilder();
                while (rs.next()) {
                    StringBuilder values = new StringBuilder();
                    values.append("(");
                    for (int i = 1; i <= columnCount; i++) {
                        Object value = rs.getObject(i);
                        if (value != null) {
                            values.append("'").append(value.toString()).append("'");
                        } else {
                            values.append("NULL");
                        }
                        if (i < columnCount) {
                            values.append(", ");
                        }
                    }
                    values.append(")");
                    insertIntoStatements.append("INSERT INTO ").append(tableName).append(" VALUES ").append(values).append(";\n");
                }

                // generate CREATE INDEX statements
                String fileName = tableName + ".sql";
                try (PrintWriter writer = new PrintWriter(fileName)) {
                    writer.println(createTableStatement.toString());
                    writer.println(insertIntoStatements.toString());
                    ResultSet indexes = metaData.getIndexInfo(null, null, tableName, false, false);
                    while (indexes.next()) {
                        String indexName = indexes.getString("INDEX_NAME");
                        if (indexName != null && !indexName.equals("sqlite_autoindex_" + tableName + "_1")) {
                            String columnName = indexes.getString("COLUMN_NAME");
                            String unique = indexes.getBoolean("NON_UNIQUE") ? "" : "UNIQUE ";
                            String indexType = indexes.getBoolean("INDEXED_ASC") ? "ASC" : "DESC";
                            String createIndexStatement = "CREATE " + unique + "INDEX " + indexName + " ON " + tableName + " (" + columnName + " " + indexType + ");";
                            writer.println(createIndexStatement);
                        }
                    }
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }
    }
}

运行该程序，将会在数据库所在目录下生成包含表结构、数据、索引和外键的备份文件。