将语句转换为准备好的java语句 static int R; stmt=conn.createStatement(); String query=“从Points+”中选择Points.Name、Points.x、Points.y,其中Points.x>=”+(x-R)+”和Points.x=“+(y-R)+”和Points.y

将语句转换为准备好的java语句 static int R; stmt=conn.createStatement(); String query=“从Points+”中选择Points.Name、Points.x、Points.y,其中Points.x>=”+(x-R)+”和Points.x=“+(y-R)+”和Points.y,java,mysql,sql,Java,Mysql,Sql,尝试以下操作: static int R; stmt = conn.createStatement(); String query = "SELECT Points.Name, Points.x, Points.y FROM Points + "WHERE Points.x>=" + (x-R) + " AND Points.x<="+ (x + R) + " AND Points.y>=" + (y - R) + " AND Points.y<="+ (y + R)

尝试以下操作:

static int R;

stmt = conn.createStatement();

String query = "SELECT Points.Name, Points.x, Points.y FROM Points + "WHERE Points.x>=" + (x-R) + " AND Points.x<="+ (x + R) + " AND Points.y>=" + (y - R) + " AND Points.y<="+ (y + R) + " AND Points.Name='" + name + "'";

rs = stmt.executeQuery(query);

将参数替换为“”,然后逐个添加。然后执行。

尝试以下操作:

static int R;

stmt = conn.createStatement();

String query = "SELECT Points.Name, Points.x, Points.y FROM Points + "WHERE Points.x>=" + (x-R) + " AND Points.x<="+ (x + R) + " AND Points.y>=" + (y - R) + " AND Points.y<="+ (y + R) + " AND Points.Name='" + name + "'";

rs = stmt.executeQuery(query);
PreparedStatement ps = null;
ps = con.prepareStatement("select concat(first_name,' ',last_name) as full_name from employee where salary between ? and ?");
int i=1;
ps.setInt(i++, 30000);
ps.setInt(i++, 40000);
rs = ps.executeQuery();
将参数替换为“”,然后逐个添加。然后执行。

静态int R;
PreparedStatement ps = null;
ps = con.prepareStatement("select concat(first_name,' ',last_name) as full_name from employee where salary between ? and ?");
int i=1;
ps.setInt(i++, 30000);
ps.setInt(i++, 40000);
rs = ps.executeQuery();
String query=“从Points.x>=?和Points.x=?以及Points.y
static int R的点中选择Points.Name、Points.x、Points.y;

String query=“从Points.x>=”的点中选择Points.Name、Points.x、Points.y?”?和Points.x=?还有要点。你在找文件。到目前为止你都试了些什么?您给出的代码甚至不是有效的Java。你读过任何教程吗?你在找文档。到目前为止你都试了些什么?您所提供的代码甚至不是有效的Java。你读过任何教程吗?
stmt.setInt(1,x-R)
-或者更可能。@JoopEggen对,这是一个简单的例子。请注意,这并不重要,您可以在大多数情况下使用
setString()
,它只会导致数据库在转换其端的数据类型时做额外的工作。
stmt.setInt(1,x-R)
-或者更可能。@JoopEggen对,这是一个快速的示例。请注意,这并不重要,您可以在大多数情况下使用
setString()
,它只会导致数据库在转换其端的数据类型时做额外的工作。