删除表信息，主外键约束提示有关问题。

com.microsoft.sqlserver.jdbc.SQLServerException: DELETE 语句与 REFERENCE 约束"FK_ZC_Admission_ZC_Nursery"冲突。该冲突发生于数据库"ZC_NmSoft"，表"dbo.ZC_Admission", column 'NurseryID'。    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerStatement.doExecuteStatement(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerStatement$StmtExecCmd.doExecute(Unknown Source)    at com.microsoft.sqlserver.jdbc.TDSCommand.execute(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(Unknown Source)    at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeUpdate(Unknown Source)    at datebase.JDBC.update(JDBC.java:55)    at sqlbean.SqlBean.deleteNursery(SqlBean.java:141)    at com.yourcompany.struts.action.CollectiveAction.deleteNursery(CollectiveAction.java:123)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)    at java.lang.reflect.Method.invoke(Method.java:597)    at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)    at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)    at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)    at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)    at java.lang.Thread.run(Thread.java:619)

package datebase;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class JDBC {    Connection conn = null;    Statement st = null;    ResultSet rs = null;    PreparedStatement ps;    public JDBC() {        try {            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");// 2005        } catch (ClassNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        try {            conn = DriverManager.getConnection(                    "jdbc:sqlserver://localhost:1433;DatabaseName=ZC_NmSoft",                    "sa", "123456");        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        try {            // 创建语句对象            st = conn.createStatement();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    public ResultSet query(String sql) {        try {            rs = st.executeQuery(sql);        } catch (SQLException e) {            System.out.println("查询操作异常：" + e);            e.printStackTrace();        }        return rs;    }    public int update(String sql) {        int i = -1;        try {            i = st.executeUpdate(sql);        } catch (SQLException e) {            e.printStackTrace();        }        return i;    }    public int executeUpdate(String sql)// 更新调用类    {        int count = 0;        try {            st = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,                    ResultSet.CONCUR_READ_ONLY);            count = st.executeUpdate(sql);        } catch (Exception ex) {            ex.printStackTrace();        }        return count;    }    public PreparedStatement preparedStatement(String sql) {        try {            ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE,                    ResultSet.CONCUR_READ_ONLY);        } catch (Exception ex) {            ex.printStackTrace();        }        return ps;    }    public void close() {        try {            st.close();        } catch (SQLException e) {            System.out.println("关闭stmt异常：" + e);            e.printStackTrace();        }        try {            conn.close();        } catch (SQLException e) {            System.out.println("关闭conn异常：" + e);            e.printStackTrace();        }    }}