[英]Refactoring this java sql code snippet
我想将这两个SQL查询合并为1,这可能吗? 不幸的是,我不是SQL专家。
我目前使用2个查询的代码段如下:
if(myFlag.equals("") || isFlagPirate.equals("N")){
//get list of available ship id, ship name as options for the ship dropdown list
sqlShipListString =
"select distinct ship.ship_id, ship.name from admiralty_branch " +
"left join ship on ship.ship_id=admiralty_branch.ship_id " +
"where admiralty_branch_id= " + admiraltyid +
" order by ship.name";
}else{
if(isFlagPirate.equals("Y")){
//get list of available ship id, ship name as options for the ship dropdown list
sqlShipListString =
"select distinct ship.ship_id, ship.name from ship " +
"left join ship_type on ship.ship_id=ship_type.ship_id " +
"left join fleet on ship_type.fleet_id=fleet.fleet_id " +
"where fleet_id= " + fleetId +
" order by ship.name";
}
}
根据要求,表结构:
**ship**
ship_id
name
**admiralty_branch**
admiralty_branch_id
ship_id
**ship_type**
ship_id
fleet_id
**fleet**
fleet_id
这是一个丑陋的解决方案。 海盗的左2个连接点与非海盗的1个连接点使模式有所不同。 我不会仅对这两个查询进行重构。 如果您有更多内容,可以考虑创建某种sqlbuilder。
public String getSql(String isFlagPirate)
{
if(myFlag .equals("") || isFlagPirate.equals("N")){
//get list of available ship id, ship name as options for the ship dropdown list
return
buildSql("admiralty_branch ", "ship on ship.ship_id=admiralty_branch.ship_id ",
"admiralty_branch_id", admiraltyid);
}else{
if(isFlagPirate.equals("Y")){
//get list of available ship id, ship name as options for the ship dropdown list
return buildSql("ship ", "ship_type on ship.ship_id=ship_type.ship_id left join fleet on ship_type.fleet_id=fleet.fleet_id ",
"fleet_id", fleetId);
}
return "";
}
}
protected String buildSql(String table, String leftjoin, String whereFieldName, String whereFieldValue)
{
return "select distinct ship.ship_id, ship.name from "+table +
"left join "+leftjoin +
"where "+whereFieldName+"= " + whereFieldValue +
" order by ship.name";
}
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