使用JOOQ的两个字段的别名

Question

i have a nasty SQl that i want transform in JOOQ

Here are the Query:

  SELECT 
    SUM(dpr.dpr_bruttopraemie_prt + dpr.dpr_sofortrabatt_prt) 
    , MAX(TO_NUMBER(DP1.dp_wert))  
      FROM deckungen deck, deckungspraemien dpr, 
        (SELECT dp.dp_id, dp.dp_wert 
              FROM  textbausteine txb, druckparameter dp 
              WHERE  dp.dp_txb_id = txb.txb_id 
              ) DP1 
      WHERE DP1.dp_id = :druckparameter_id;

As you can see, i need to make alias from a select with two Fields.

dp.dp_id, dp.dp_wert 

that im going to used it on some other parts.

How i can i get it done?

i've seen

.asField() 

Funktion but it only make alias for one column.

PS: The actual Query are a lot more complicated. So i wrote a simpler one. With hoping that it's satisfied the SQL ORACLE Dialect.

Answer 1

I'm assuming that you're using the code generator, so you have generated objects available for your tables like DECKUNGEN . I'm also assuming you're using these static imports:

import static org.jooq.impl.DSL.*;                  // The jOOQ API
import static com.example.myapp.generated.Tables.*; // Your generated tables

You can then write:

Deckungen deck = DECKUNGEN.as("deck");
Deckungspraemien dpr = DECKUNGSPRAEMIEN.as("dpr");
Textbausteine txb = TEXTBAUSTEINE.as("txb");
Druckparameter dp = DRUCKPARAMETER.as("dp");

Table<?> dp1 = table(
    select(dp.DP_ID, dp.DP_WERT)
   .from(txb, dp)
   .where(dp.DP_TXB_ID.eq(txb.TXB_ID))
).as("dp1");

Record2<BigDecimal, BigDecimal> result =
using(configuration)
  .select(
     sum(dpr.DPR_BRUTTOPRAEMIE_PRT.plus(dpr.DPR_SOFORTRABATT_PRT)),
     max(field("to_number({0})", BigDecimal.class, dp1.field(dp.DP_WERT))))
  .from(deck, dpr, dp1)
  .where(dp1.field(dp.DP_ID).eq(druckparameterId))
  .fetchOne();

Some explanations

• jOOQ currently doesn't have a built-in TO_NUMBER() function, but you can easily roll your own using DSL.field(String) and similar overloads. For more detail, refer to the manual's section about plain SQL
• A derived table can be created most easily by using the DSL.table(Select) operator.
• Columns from a derived table can be dereferenced using Table.field() methods, in particular the Table.field(Field) , which tries to find a field by the same name as the argument field, retaining the argument field's type information.

Side-note

I don't think your query is correct as you're simply creating cartesian products between your tables deck , dpr , and dp1 . Specifically, the SUM() is quite likely to be wrong, whereas MAX() is simply calculated inefficiently.