转换结果从SQL阵列设置为字符串数组 [英] Convert a Result Set from SQL Array to Array of Strings

问题描述

我查询INFORMATION_SCHEMA.COLUMNS表在我的PostgreSQL数据库。使用一个表名，结果集查找所有的列名，类型，以及它是否是可空（除了主键，ID）。这是正在使用的查询：

  SELECT列名，IS_NULLABLE，DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS
其中较低（TABLE_NAME）=低（'TABLE1'）AND COLUMN_NAME！='ID'
ORDER BY ORDINAL_POSITION;
 

我对这些结果的字符串数组，我试图用的ResultSet方法的getArray（字符串columnLabel）来避免通过结果循环。我想存储在字符串数组返回数组，却得到了一个类型不匹配错误（类型不匹配：不能从数组转换为String [] 的）。

有没有办法到SQL Array对象转换或强制转换为String []？

相关code：

的String [] COLUMNNAME，类型，可为空;//获取字段名称，类型和放大器;空性
查询字符串=SELECT列名，IS_NULLABLE，DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS
        +WHERE较低（TABLE_NAME）=低（'+ tableName值+'）AND COLUMN_NAME！='ID'
        +ORDER BY ORDINAL_POSITION尝试{
    结果集RS = Query.executeQueryWithRS（C，查询）;
    COLUMNNAME = rs.getArray（rs.getArray（栏）;
    类型= rs.getArray（DATA_TYPE）;
    可空= rs.getArray（IS_NULLABLE）;
}赶上（例外五）{
    e.printStackTrace（）;
}


解决方案

使用：

 阵列A = rs.getArray（IS_NULLABLE）;
的String [] =可空（字符串[]）a.getArray（）;
 

作为解释这里

阵列是SQL类型，的getArray（）返回一个对象转换为Java数组。

I am querying the information_schema.columns table in my PostgreSQL database. Using a table name, the result set finds all the column names, type, and whether it is nullable (except for the primary key, 'id'). This is the query being used:

SELECT column_name, is_nullable,data_type FROM information_schema.columns
WHERE lower(table_name) = lower('TABLE1') AND column_name != 'id'
ORDER BY ordinal_position;

I have a string array for each of these results and I am trying to use the ResultSet method getArray(String columnLabel) to avoid looping through the results. I want to store the returned Arrays in the string arrays, but get a type mismatch error ("Type mismatch: cannot convert from Array to String[]").

Is there a way to convert or typecast the SQL Array object to a String[]?

Relevant Code:

String[] columnName, type, nullable;

//Get Field Names, Type, & Nullability 
String query = "SELECT column_name, is_nullable,data_type FROM information_schema.columns "
        + "WHERE lower(table_name) = lower('"+tableName+"') AND column_name != 'id' "
        + "ORDER BY ordinal_position";

try{
    ResultSet rs = Query.executeQueryWithRS(c, query);
    columnName = rs.getArray(rs.getArray("column_name");
    type = rs.getArray("data_type");
    nullable = rs.getArray("is_nullable");
}catch (Exception e) {
    e.printStackTrace();
}

解决方案

Use:

Array a = rs.getArray("is_nullable");
String[] nullable = (String[])a.getArray();

As explained here

Array is SQL type, getArray() returns an object to cast to java array.

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