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59 lines
1.9 KiB
Markdown
59 lines
1.9 KiB
Markdown
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# New Features
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There are a bunch of new features, that are not fully documented yet. If you would like to contribute documentation, please let me know.
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## Preprocessor generator for columns/tables
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You'll need boost 1.50 or greater to use this feature by niXman:
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```C++
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#include <sqlpp11/ppgen.h>
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SQLPP_DECLARE_TABLE(
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(tab_person)
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,
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(id , int , SQLPP_AUTO_INCREMENT)
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(name , varchar(255), SQLPP_NOT_NULL )
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(feature, int , SQLPP_NOT_NULL )
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)
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```
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See `examples/ppgen.hpp`.
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## Union
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Unions are now supported. The arguments need to have the same names and types in their columns.
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```C++
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db(select(t.alpha).from(t).where(true)
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.union_distinct(select(f.epsilon.as(t.alpha)).from(f).where(true)));
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db(select(t.alpha).from(t).where(true)
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.union_all(select(f.epsilon.as(t.alpha)).from(f).where(true)));
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```
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## With
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sqlpp11 supports common table expressions:
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```C++
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auto x = sqlpp::cte(sqlpp::alias::x).as(select(all_of(t)).from(t));
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db(with(x)(select(x.alpha).from(x).where(true)));
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```
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## Custom Queries
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This allows you to combine building blocks of sqlpp11 into custom queries, for instance a SELECT..INTO which is not supported yet.
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```C++
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// A custom (select ... into) with adjusted return type
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// The first argument with a return type is the select,
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// but the custom query is really an insert. Thus, we tell it so.
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db(custom_query(select(all_of(t)).from(t), into(f))
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.with_result_type_of(insert_into(f)));
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```
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## Schema-qualified tables
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sqlpp11 assumes that you're connection addresses one database, normally. But you can tell it about other databases using the `sqlpp::schema_t` and instantiating schema-qualified tables with it:
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```C++
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auto schema = db.attach("lorem_ipsum");
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auto s = schema_qualified_table(schema, TabSample{}).as(sqlpp::alias::x)
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// s now represents "lorem_ipsum.tab_sample as x"
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// s can be used like any other table in the code
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```
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