[英]Exporting database to csv file with java
所以我在互聯網上找到了這段代碼,基本上它可以做的是從數據庫備份所有表,我的問題是在這一行:
res = st.executeQuery("select * from xcms." + tableName);
我收到以下異常:SQLException 信息
xcms
是做什么的代表? 我還能在這里放什么?
res = st.executeQuery("select * from " + tableName);
順便說一句,如果我刪除 xcms。 像這樣說^,我只能保存第一個表而不是所有表,thx
源代碼網頁:
public static void main(String[] args) {
Connection con = null;
String url = "jdbc:mysql://localhost:3306/";
String db = "gg";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "";
FileWriter fw;
try {
Class.forName(driver);
con = DriverManager.getConnection(url + db, user, pass);
Statement st = con.createStatement();
ResultSet res = st.executeQuery("SELECT table_name FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = 'gg'");
List<String> tableNameList = new ArrayList<String>();
while (res.next()) {
tableNameList.add(res.getString(1));
}
String filename = "C:\\Users\\Angel Silva\\Documents";
for (String tableName : tableNameList) {
int k = 0;
int j = 1;
System.out.println(tableName);
List<String> columnsNameList = new ArrayList<String>();
res = st.executeQuery("select * from " + tableName);
int columnCount = getColumnCount(res);
try {
fw = new FileWriter("C:\\Users\\Angel Silva\\Documents\\popo1121.csv");
for (int i = 1; i <= columnCount; i++) {
fw.append(res.getMetaData().getColumnName(i));
fw.append(",");
}
fw.append(System.getProperty("line.separator"));
while (res.next()) {
for (int i = 1; i <= columnCount; i++) {
if (res.getObject(i) != null) {
String data = res.getObject(i).toString();
fw.append(data);
fw.append(",");
} else {
String data = "null";
fw.append(data);
fw.append(",");
}
}
fw.append(System.getProperty("line.separator"));
}
fw.flush();
fw.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
con.close();
} catch (ClassNotFoundException cnfe) {
System.err.println("Could not load JDBC driver");
cnfe.printStackTrace();
}catch (SQLException sqle) {System.err.println("SQLException information");}
}
public static int getRowCount(ResultSet res) throws SQLException {
res.last();
int numberOfRows = res.getRow();
res.beforeFirst();
return numberOfRows;
}
public static int getColumnCount(ResultSet res) throws SQLException {
return res.getMetaData().getColumnCount();
}
}
這是我用的:
public void sqlToCSV (String query, String filename){
log.info("creating csv file: " + filename);
try {
FileWriter fw = new FileWriter(filename + ".csv");
if(conn.isClosed()) st = conn.createStatement();
ResultSet rs = st.executeQuery(query);
int cols = rs.getMetaData().getColumnCount();
for(int i = 1; i <= cols; i ++){
fw.append(rs.getMetaData().getColumnLabel(i));
if(i < cols) fw.append(',');
else fw.append('\n');
}
while (rs.next()) {
for(int i = 1; i <= cols; i ++){
fw.append(rs.getString(i));
if(i < cols) fw.append(',');
}
fw.append('\n');
}
fw.flush();
fw.close();
log.info("CSV File is created successfully.");
conn.close();
} catch (Exception e) {
log.fatal(e);
}
}
xms
代表數據庫名稱,在您已經建立與數據庫的Connection
的 java 程序中的連接中:
(DriverManager.getConnection(url + db, user, pass);
字符串db
是要連接的數據庫的名稱。
所以不需要xms.
.例如使用這個查詢:
"SELECT * FROM "+tableName+";"
這是在您連接的數據庫中執行的,例如代碼中的gg
。
對於編寫 CSV 文件chillyfacts.com/export-mysql-table-csv-file-using-java/可能有幫助!
SELECT * FROM <MENTION_TABLE_NAME_HERE> INTO OUTFILE <FILE_NAME> FIELDS TERMINATED BY ',';
例子:
SELECT * FROM topic INTO OUTFILE 'D:\5.csv' FIELDS TERMINATED BY ',';
使用 opencsv 依賴項以最少的代碼行將 SQL 數據導出到 CSV。
import com.opencsv.CSVWriter;
import java.io.FileWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class CsvWriter {
public static void main(String[] args) throws Exception {
CSVWriter writer = new CSVWriter(new FileWriter("filename.csv"), '\t');
Boolean includeHeaders = true;
Statement statement = null;
ResultSet myResultSet = null;
Connection connection = null;
try {
connection = //make database connection here
if (connection != null) {
statement = connection.createStatement();
myResultSet = statement.executeQuery("your sql query goes here");
writer.writeAll(myResultSet, includeHeaders);
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
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