Merge tag '0.36' into develop

Several breaking changes:

  * `from(a,b)` not allowed anymore, please use explicit joins
  * `where(true)` not allowed anymore, please use `.unconditionally()` or sqlpp::value(true)
  * `some_sql_expression and true` not allowed anymore, please use `tab.col == sqlpp::value(true)` if you really want to express this.
  * `having(expression)` requires `expression` to be made of aggregates, e.g. columns named in `group_by()` or aggregate functions like `count()` or constant values.
  * `where()` and `having()` accept only one parameter

Several more clauses are now available as free functions.

Lots of additional tests.

ChangeLog.md

@@ -0,0 +1,109 @@
+Important changes in sqlpp11
+============================
+
+Breaking changes in 0.36:
+-------------------------
+__Abstract__:
+
+One of the main motivations of sqlpp11 is to prevent SQL programming mistakes at compile time. The following changes prevent reported mishaps.
+  * `from(a,b)` not allowed anymore, please use explicit joins
+  * `where(true)` not allowed anymore, please use `.unconditionally()` or sqlpp::value(true)
+  * `some_sql_expression and true` not allowed anymore, please use `tab.col == sqlpp::value(true)` if you really want to express this.
+  * `having(expression)` requires `expression` to be made of aggregates, e.g. columns named in `group_by()` or aggregate functions like `count()` or constant values.
+  * `where()` and `having` accept only one parameter
+
+__Explicit joins required__:
+
+Up until sqlpp11-0.35 you could write something like
+
+```
+auto result = db(select(all_of(a), all_of(b))
+                 .from(a,b)
+                 .where(true));
+```
+
+Using this syntax in `from()`, it was expected to have the join condition implicitly in the `where()` call.
+But there is no reliable way to tell whether or not that condition is there. Or, if there definitely is none, whether
+it was omitted on purpose or by accident.
+In one case, an accidentally omitted join condition in the `where()` brought a production system to a screeching halt.
+
+In order to prevent this in the future, sqlpp11 now requires you to join table explicitly, including an explicit join condition, e.g.
+
+```
+auto result = db(select(all_of(a), all_of(b))
+                 .from(a.join(b).on(a.b == b.id))
+                 .where(true));
+```
+
+Most joins, (`join`/`inner_join`, `left_outer_join`, `right_outer_join` and `outer_join`) require a join condition to given via `on()`.
+The join condition has to be some sqlpp11 boolean expression.
+
+In those rare cases, when you really need a cross join, you can also use `cross_join()` which has no join condition, of course.
+
+```
+auto result = db(select(all_of(a), all_of(b))
+                 .from(a.cross_join(b))
+                 .where(true));
+```
+
+__Use `.unconditionally()`__
+
+If you want to select/update/remove all rows, earlier versions of sqlpp11 required the use of `where(true)`. Since version 0.36, use `unconditionally()`, for instance:
+```
+auto result = db(select(all_of(t)).from(t).unconditionally());
+```
+
+__Use `sqlpp::value()` to wrap bool values in boolean expressions__
+
+Lets say you had
+
+```
+struct X
+{
+    int a;
+    int b;
+};
+auto x = X{};
+```
+
+Then earlier versions of sqlpp11 would compile the following expression:
+
+```
+select(all_of(t)).from(t).where(x.a == x.a or t.b == t.b);
+```
+
+What you probably meant was:
+
+```
+select(all_of(t)).from(t).where(t.a == x.a and t.b == x.b);
+```
+
+In order to prevent this kind of mistake, boolean operators in sql expressions require sqlpp boolean expressions as operators.
+The library also requires the types of the left/right hand side operands of a comparison to be different, so that `t.a < t.a` does not compile any more.
+
+In the rare case you really have a bool value that you want to use a boolean sql expression, you have to wrap it in sqlpp::value(x), e.g.
+
+```
+select(all_of(t)).from(t).where(sqlpp::value(x.a == 17) and t.b == x.b);
+```
+
+__`having()` requires aggregate expressions__
+
+In older versions, the following code was allowed:
+
+```
+select(all_of(t)).from(t).where(t.a > 7).having(t.b != "");
+```
+
+As of sqlpp11-0.36, the having argument must be made of aggregate columns or functions, e.g.
+
+```
+select(all_of(t)).from(t).unconditionally().group_by(t.b).having(t.b != "", avg(t.c) < 42);
+```
+
+__`where()` and `having` accept only one expression__
+
+In older versions, `where()` and `having()` would accept more than one argument and combine those arguments with `and`.
+I am not sure this was ever used. So it just made life harder for the compiler.
+
+As of version 0.36, `where()` and `having()` accept only one parameter.

README.md

@@ -145,11 +145,22 @@ Basic usage:
 __Linux install:__
 git clone date library, needed connectors, cmake and make install them.
 
-create DDL files (like mysql: 'show create table MyDatabase.MyTable', but remove backticks), create headers for them with provided python script:
+
+__Create DDL files__:
+``` 
+mysql: 'show create table MyDatabase.MyTable' #or
+mysqldump --no-data MyDatabase > MyDatabase.sql
+
+```
+Create headers for them with provided python script:
 ```
 %sqlpp11_dir%/scripts/ddl2cpp ~/temp/MyTable.ddl  ~/temp/MyTable %DatabaseNamespaceForExample%
 ```
-include generated header (MyTable.h), that's all
+(In case you're getting notes about unsupported column type take a look at the other datatypes in sqlpp11/data_types. They are not hard to implement.)
+
+Include generated header (MyTable.h), that's all
+
+
 
 
 License:

scripts/ddl2cpp

@@ -128,6 +128,8 @@ types = {
     'date' : 'day_point',
     'datetime' : 'time_point',
     'timestamp' : 'time_point',
+    'enum' : 'text', # MYSQL
+    'set' : 'text',  # MYSQL
     }
 
 
@@ -145,7 +147,7 @@ print('#include <' + INCLUDE + '/char_sequence.h>', file=header)
 print('', file=header)
 print('namespace ' + namespace, file=header)
 print('{', file=header)
-
+DataTypeError = False;
 for create in tableCreations:
     sqlTableName = create.tableName
     tableClass = toClassName(sqlTableName)
@@ -181,7 +183,11 @@ for create in tableCreations:
         print('            const T& operator()() const { return ' + columnMember + '; }', file=header)
         print('          };', file=header)
         print('      };', file=header)
-        traitslist = [NAMESPACE + '::' + types[sqlColumnType]];
+        try:
+            traitslist = [NAMESPACE + '::' + types[sqlColumnType]];
+        except KeyError as e:
+            print ('Error: datatype "'  + sqlColumnType + '"" is not supported.')
+            DataTypeError = True
         requireInsert = True
         if column.hasAutoValue:
             traitslist.append(NAMESPACE + '::tag::must_not_insert');
@@ -217,4 +223,10 @@ for create in tableCreations:
 
 print('}', file=header)
 print('#endif', file=header)
-
+if (DataTypeError):
+    print("Error: unsupported datatypes." )
+    print("Possible solutions:")
+    print("A) Implement this datatype (examples: sqlpp11/data_types)" )
+    print("B) Extend/upgrade ddl2cpp (edit types map)" )
+    print("C) Raise an issue on github" )
+    sys.exit(10) #return non-zero error code, we might need it for automation