[use manual] add more manuals (#742)

* 1. add group_by
2. add property reference
3. mv nebula 127 ..> to nebula>

* address judy & amber's comments

* add fetch

* add order by

docs/get-started.md

@@ -112,7 +112,7 @@ To connect to the graph server, run
 
 Welcome to Nebula Graph (Version 0.1)
 
-(user@127.0.0.1) [(none)]>
+nebula>
 ```
 
 If you have any questions or concerns about the deployment procedures, please do not hesitate to open an issue on [GitHub](https://github.com/vesoft-inc/nebula/issues).
@@ -291,15 +291,15 @@ There are three kinds of tags (_course_, _building_ and _student_) and two edge
 
 To list all existing spaces:
 ```
-(user@127.0.0.1) [(none)]> SHOW SPACES;
+nebula> SHOW SPACES;
 ```
 
 To create a new space named myspace_test2 :
 ```
-(user@127.0.0.1) [(none)]> CREATE SPACE myspace_test2(partition_num=1, replica_factor=1);
+nebula> CREATE SPACE myspace_test2(partition_num=1, replica_factor=1);
 
 -- Use this space
-(user@127.0.0.1) [(none)]> USE myspace_test2;
+nebula> USE myspace_test2;
 ```
 `replica_factor` specifies the number of replicas in the cluster.
 
@@ -309,32 +309,32 @@ To create a new space named myspace_test2 :
 
 The `CREATE TAG` statement defines a tag, with a type name and an attribute list.
 ```
-(user@127.0.0.1) [(none)]> CREATE TAG course(name string, credits int);
-(user@127.0.0.1) [(none)]> CREATE TAG building(name string);
-(user@127.0.0.1) [(none)]> CREATE TAG student(name string, age int, gender string);
+nebula> CREATE TAG course(name string, credits int);
+nebula> CREATE TAG building(name string);
+nebula> CREATE TAG student(name string, age int, gender string);
 ```
 The `CREATE EDGE` statement defines an edge type.
 ```
-(user@127.0.0.1) [(none)]> CREATE EDGE like(likeness double);
-(user@127.0.0.1) [(none)]> CREATE EDGE select(grade int);
+nebula> CREATE EDGE like(likeness double);
+nebula> CREATE EDGE select(grade int);
 ```
 
 To list the tags and edge types that we just created：
 ```
 -- Show tag list
-(user@127.0.0.1) [(none)]> SHOW TAGS;
+nebula> SHOW TAGS;
 
 -- Show edge type list
-(user@127.0.0.1) [(none)]> SHOW EDGES;
+nebula> SHOW EDGES;
 ```
 
 To show the attributes of a tag or an edge type:
 ```
 -- Show attributes of a tag
-(user@127.0.0.1) [(none)]> DESCRIBE TAG student;
+nebula> DESCRIBE TAG student;
 
 -- Show attributes of an edge type
-(user@127.0.0.1) [(none)]> DESCRIBE EDGE like;
+nebula> DESCRIBE EDGE like;
 ```
 
 
@@ -345,31 +345,31 @@ Insert the vertices and edges based on the graph above.
 ```
 
 -- Insert vertices
-(user@127.0.0.1) [(none)]> INSERT VERTEX student(name, age, gender) VALUES 200:("Monica", 16, "female");
-(user@127.0.0.1) [(none)]> INSERT VERTEX student(name, age, gender) VALUES 201:("Mike", 18, "male");
-(user@127.0.0.1) [(none)]> INSERT VERTEX student(name, age, gender) VALUES 202:("Jane", 17, "female");
-(user@127.0.0.1) [(none)]> INSERT VERTEX course(name, credits),building(name) VALUES 101:("Math", 3, "No5");
-(user@127.0.0.1) [(none)]> INSERT VERTEX course(name, credits),building(name) VALUES 102:("English", 6, "No11");
+nebula> INSERT VERTEX student(name, age, gender) VALUES 200:("Monica", 16, "female");
+nebula> INSERT VERTEX student(name, age, gender) VALUES 201:("Mike", 18, "male");
+nebula> INSERT VERTEX student(name, age, gender) VALUES 202:("Jane", 17, "female");
+nebula> INSERT VERTEX course(name, credits),building(name) VALUES 101:("Math", 3, "No5");
+nebula> INSERT VERTEX course(name, credits),building(name) VALUES 102:("English", 6, "No11");
 
 ```
 
 ```
 -- Insert edges
-(user@127.0.0.1) [(none)]> INSERT EDGE select(grade) VALUES 200 -> 101:(5);
-(user@127.0.0.1) [(none)]> INSERT EDGE select(grade) VALUES 200 -> 102:(3);
-(user@127.0.0.1) [(none)]> INSERT EDGE select(grade) VALUES 201 -> 102:(3);
-(user@127.0.0.1) [(none)]> INSERT EDGE select(grade) VALUES 202 -> 102:(3);
-(user@127.0.0.1) [(none)]> INSERT EDGE like(likeness) VALUES 200 -> 201:(92.5);
-(user@127.0.0.1) [(none)]> INSERT EDGE like(likeness) VALUES 201 -> 200:(85.6);
-(user@127.0.0.1) [(none)]> INSERT EDGE like(likeness) VALUES 201 -> 202:(93.2);
+nebula> INSERT EDGE select(grade) VALUES 200 -> 101:(5);
+nebula> INSERT EDGE select(grade) VALUES 200 -> 102:(3);
+nebula> INSERT EDGE select(grade) VALUES 201 -> 102:(3);
+nebula> INSERT EDGE select(grade) VALUES 202 -> 102:(3);
+nebula> INSERT EDGE like(likeness) VALUES 200 -> 201:(92.5);
+nebula> INSERT EDGE like(likeness) VALUES 201 -> 200:(85.6);
+nebula> INSERT EDGE like(likeness) VALUES 201 -> 202:(93.2);
 ```
 
 ## Sample Queries
 
 Q1. Find the vertexes that 201 likes:
 
 ```
-(user@127.0.0.1) [(none)]> GO FROM 201 OVER like;
+nebula> GO FROM 201 OVER like;
 
 =======
 |  id |
@@ -383,7 +383,7 @@ Q1. Find the vertexes that 201 likes:
 Q2. Find the vertexes that 201 likes, whose age are greater than 17. Return their name, age and gender, and alias the columns as Friend, Age and Gender, respectively.
 
 ```
-(user@127.0.0.1) [(none)]> GO FROM 201 OVER like WHERE $$.student.age >= 17 YIELD $$.student.name AS Friend, $$.student.age AS Age, $$.student.gender AS Gender;
+nebula> GO FROM 201 OVER like WHERE $$.student.age >= 17 YIELD $$.student.name AS Friend, $$.student.age AS Age, $$.student.gender AS Gender;
 
 =========================
 | Friend | Age | Gender |
@@ -402,7 +402,7 @@ Q3. Find the selected courses and corresponding grades of students liked by 201.
 ```
 
 -- By pipe
-(user@127.0.0.1) [(none)]> GO FROM 201 OVER like | GO FROM $-.id OVER select YIELD $^.student.name AS Student, $$.course.name AS Course, select.grade AS Grade;
+nebula> GO FROM 201 OVER like | GO FROM $-.id OVER select YIELD $^.student.name AS Student, $$.course.name AS Course, select.grade AS Grade;
 
 =============================
 | Student |  Course | Grade |
@@ -415,7 +415,7 @@ Q3. Find the selected courses and corresponding grades of students liked by 201.
 -----------------------------
 
 -- By temporary variable
-(user@127.0.0.1) [(none)]> $a=GO FROM 201 OVER like; GO FROM $a.id OVER select YIELD $^.student.name AS Student, $$.course.name AS Course, select.grade AS Grade;
+nebula> $a=GO FROM 201 OVER like; GO FROM $a.id OVER select YIELD $^.student.name AS Student, $$.course.name AS Course, select.grade AS Grade;
 
 =============================
 | Student |  Course | Grade |

docs/manual_doc/Functions_and_Operators/Comparison_Functions_and_Operators.md

@@ -20,14 +20,14 @@ Comparison operations result in a value of _true_ and _false_.
 Equal. String comparisons are case-sensitive. Values of different type are not equal.
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 'A' == 'a';
+nebula> YIELD 'A' == 'a';
 ==============
 | ("A"=="a") |
 ==============
 | false |
 --------------
 
-(user@127.0.0.1) [(none)]> YIELD '2' == 2;
+nebula> YIELD '2' == 2;
 ============
 | ("2"==2) |
 ============
@@ -40,7 +40,7 @@ Equal. String comparisons are case-sensitive. Values of different type are not e
 Greater than： 
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 3 > 2;
+nebula> YIELD 3 > 2;
 =========
 | (3>2) |
 =========
@@ -53,7 +53,7 @@ Greater than：
 Greater than or equal:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 2 >= 2;
+nebula> YIELD 2 >= 2;
 ==========
 | (2>=2) |
 ==========
@@ -66,7 +66,7 @@ Greater than or equal:
 Less than:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 2.0 < 1.9;
+nebula> YIELD 2.0 < 1.9;
 =======================
 | (2.000000<1.900000) |
 =======================
@@ -79,7 +79,7 @@ Less than:
 Less than or equal:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 0.11 <= 0.11;
+nebula> YIELD 0.11 <= 0.11;
 ========================
 | (0.110000<=0.110000) |
 ========================
@@ -92,7 +92,7 @@ Less than or equal:
 Not equal:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 1 != '1'
+nebula> YIELD 1 != '1'
 ============
 | (1!="1") |
 ============

docs/manual_doc/Functions_and_Operators/Functions_and_Operator_Reference.md

@@ -1,4 +1,4 @@
-|  Name    |  Description    | 
+|  ***Name***    |  ***Description***    | 
 |:----|:----:|
 |  abs()      |  Return the absolute value      | 
 |  acos()  |  Return the arc cosine | 

docs/manual_doc/Functions_and_Operators/Group_By_Function.md

@@ -0,0 +1,26 @@
+
+# Aggregate (Group by) function
+
+The `GROUP BY` functions  are similar with SQL. It can only be applied in the `YIELD`-syntax.
+
+|Name | Description |
+|:----|:----:|
+| AVG() | Return the average value of the argument |
+| COUNT() | Return the number of records |
+| COUNT(DISTINCT) | Return the number of different values |
+| MAX() | Return the maximum value |
+| MIN() | Return the minimum value |
+| STD() | Return the population standard deviation | 
+| SUM()	| Return the sum |
+
+All the functions above can only applies for int64 and double.
+
+### example
+
+```
+nebula> GO FROM 1 OVER e1 | YIELD $-.id AS fid, COUNT(*) AS cnt GROUP BY fid
+-- for each fid, return the occurrence count.
+
+nebula> GO FROM 1 YIELD e1._dst AS fid, e1.prop1 AS prop1 | YIELD fid, SUM(prop1) GROUP BY fid
+-- for each fid, return the sum of prop1.
+```

docs/manual_doc/Functions_and_Operators/Logical_Operators.md

@@ -1,4 +1,4 @@
-|  Name    |  Description    | 
+|  ***Name***    |  ***Description***    | 
 |:----|:----:|
 |   &&     |   Logical AND     | 
 |   !    |   Logical NOT     | 
@@ -12,7 +12,7 @@ In nGQL, nonzero numbers are evaluated to _true_. The precedence of the operator
 Logical AND:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD -1 && true;
+nebula> YIELD -1 && true;
 ================
 | (-(1)&&true) |
 ================
@@ -25,7 +25,7 @@ Logical AND:
 Logical NOT:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD !(-1);
+nebula> YIELD !(-1);
 ===========
 | !(-(1)) |
 ===========
@@ -39,7 +39,7 @@ Logical NOT:
 Logical OR:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 1 || !1;
+nebula> YIELD 1 || !1;
 =============
 | (1||!(1)) |
 =============

docs/manual_doc/Functions_and_Operators/Operator_Precedence.md

@@ -16,7 +16,7 @@ For operators from the same precedence level within an expression, evaluation is
 Examples:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 2+3*5;
-(user@127.0.0.1) [(none)]> YIELD (2+3)*5;
+nebula> YIELD 2+3*5;
+nebula> YIELD (2+3)*5;
 ```
 

docs/manual_doc/Functions_and_Operators/Order_By_Function.md

@@ -0,0 +1,22 @@
+# Order By Function
+
+Similar with SQL, `ORDER BY` can be used to sort in ascending (`ASC`) or descending (`DESC`) order for return results.
+And it can only be used in the `PIEP`-syntax ("|")
+
+```
+| ORDER BY <prop> ASC | DESC [, <prop> ASC | DESC ...] 
+```
+By default, `ORDER BY` sorts in ascending order if no ASC or DESC is given.
+
+### Example
+
+```
+nebula> FETCH PROP ON player 1,2,3,4 YIELD player.age AS age, player.weight as weight | ORDER BY $-.age, $-.weight DESC  
+-- get four of vertices and sort by their age begin with the youngest one, and for those with the same age, sort by their weight. 
+```
+(see `FETCH` for the usage)
+
+```
+nebula> GO FROM 1 OVER edge2 YIELD $^.t1.prop1 AS s1_p1, edge2.prop2 AS e2_p2, $$.t3.prop3 AS d3_p3 | ORDER BY s1_p1 ASC, e2_p2 DESC, d3_p3 ASC
+```
+For a group of returned tuples <s1_p1, e2_p2, d3_p3>, first sort in ascending order of s1_p1, then in descending order of e2_p2, finally ascending order of d3_p3.

docs/manual_doc/Functions_and_Operators/Type_Conversion.md

@@ -1 +1,3 @@
+<!---
 Not supported yet
+--->

docs/manual_doc/Language_Structure/Comment_Syntax.md

@@ -8,14 +8,15 @@ Nested comments are not supported
 The following example demonstrates all these comment styles:
 
 ```
-(user@127.0.0.1) [(none)]> YIELD 1+1     # This comment continues to the end of line
-(user@127.0.0.1) [(none)]> YIELD 1+1     -- This comment continues to the end of line
-(user@127.0.0.1) [(none)]> YIELD 1+1     // This comment continues to the end of line
-(user@127.0.0.1) [(none)]> YIELD 1 /* this is an in-line comment */ + 1
-(user@127.0.0.1) [(none)]> YIELD 11 + \  
-/* Multiple-line comment \
-Use backslash \
-as line break. \
+nebula> -- Do nothing this line
+nebula> YIELD 1+1     # This comment continues to the end of line
+nebula> YIELD 1+1     -- This comment continues to the end of line
+nebula> YIELD 1+1     // This comment continues to the end of line
+nebula> YIELD 1       /* this is an in-line comment */ + 1
+nebula> YIELD 11 +             \  
+/* Multiple-line comment       \
+Use backslash as line break.   \
 */ 12
 ```
+The backslash `\` at the line of line indicates a line break.
 

docs/manual_doc/Language_Structure/Identifier_Case_Sensitivity.md

@@ -3,16 +3,16 @@ In Nebula Graph, Identifiers are case-sensitive.
 The following statement would not work because it refers to a space both as 'my_space' and as 'MY_SPACE':
 
 ```
-(user@127.0.0.1) [(none)]> CREATE SPACE my_space();
-(user@127.0.0.1) [(none)]> use MY_SPACE;
+nebula> CREATE SPACE my_space();
+nebula> use MY_SPACE;
 ```
 
 However, keywords and reserved words are case-insensitive. 
 
 The following statements are equivalent:
 ```
-(user@127.0.0.1) [(none)]> show spaces;
-(user@127.0.0.1) [(none)]> SHOW SPACES;
-(user@127.0.0.1) [(none)]> SHOW spaces;
-(user@127.0.0.1) [(none)]> show spaces;
+nebula> show spaces;
+nebula> SHOW SPACES;
+nebula> SHOW spaces;
+nebula> show spaces;
 ```

docs/manual_doc/Language_Structure/Literal_Values/Boolean_Literals.md

@@ -1,7 +1,7 @@
 The boolean literals `TRUE` and `FALSE` can be written in any lettercase.
 
 ```
-(user@127.0.0.1) [(none)]> yield TRUE, true, FALSE, false, FalsE
+nebula> yield TRUE, true, FALSE, false, FalsE
 =========================================
 |  true |  true | false | false | false |  
 =========================================

docs/manual_doc/Language_Structure/Literal_Values/NULL_Values.md

@@ -1,5 +1,5 @@
 <!---
 >NOTICE: NULL and NOT NULL are NOT FULLY SUPPORTED YET!
 
-The NULL value means “no data.” NULL can be written in any lettercase. Be aware that the NULL value is different from values such as 0 for interges or empty string.
+The NULL value means “no data.” NULL can be written in any letter cases. Be aware that the NULL value is different from values such as 0 for interges or empty string.
 --->