Java SQL“ERROR：Relation”Table_Name"不存在“ [英] Java SQL "ERROR: Relation "Table_Name" does not exist"

问题描述

我正在尝试将netbeans连接到我的postgresql数据库。连接似乎有效，因为我在连接时没有出现任何错误或异常，getCatalog（）等方法也会返回正确答案。

I'm trying to connect netbeans to my postgresql database. The connection seems to have worked as I don't get any errors or exceptions when just connecting, methods such as getCatalog() also return the correct answers.

但是当我尝试运行一个简单的SQL语句我收到错误错误：关系TABLE_NAME不存在，其中TABLE_NAME是我的任何一个表，它存在于数据库中。这是我的代码：

But when I try to run a simple SQL statement I get the error "ERROR: relation "TABLE_NAME" does not exist", where TABLE_NAME is any one of my tables which DO exist in the database. Here's my code:

    Statement stmt = con.createStatement();

    ResultSet rs;

    String query = "SELECT * FROM clients";

    rs = stmt.executeQuery(query);

我以为netbeans可能找不到表，因为它没有查看默认模式（public ），有没有办法在java中设置架构？

I was thinking that netbeans might not be finding the tables because it's not looking in the default schema (public), is there a way of setting the schema in java?

编辑：我的连接代码。数据库名称是Cinemax，当我省略语句代码时，我没有错误。

My connection code. The database name is Cinemax, when I leave out the statement code, I get no errors.

    String url = "jdbc:postgresql://localhost:5432/Cinemax";
    try{

    try {
        Class.forName("org.postgresql.Driver");
    } catch (ClassNotFoundException cnfe) {
        System.err.println("Couldn't find driver class:");
        cnfe.printStackTrace();
    }

    Connection con = DriverManager.getConnection( url,"postgres","desertrose147");

推荐答案

我怀疑你使用双引号创建表格，例如Clients或其他一些大写/小写字符的组合，因此表名现在区分大小写。

I suspect you created the table using double quotes using e.g. "Clients" or some other combination of upper/lowercase characters and therefor the table name is case sensitive now.

声明是什么

 SELECT table_schema, table_name
 FROM information_schema.tables 
 WHERE lower(table_name) = 'clients'

返回？

如果返回的表名不是小写，在引用它时必须使用双引号，如下所示：

If the table name that is returned is not lowercase you have to use double quotes when referring to it, something like this:

String query = "SELECT * FROM \"Clients\"";

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