SQL

Below the SQL dialect supported by NitrosBase is described. All the examples in this document use the database described in the following documents: Multi-modelity and Demo database.

CREATE TABLE

Syntax

CREATE TABLE [IF NOT EXISTS] tbl_name 
    ( create_definition [, create_definition] ... )
 
create_definition:
    col_name data_type 
      [NOT NULL | NULL] [DEFAULT literal]
      [PRIMARY KEY]
    | [CONSTRAINT [symbol]] FOREIGN KEY
      [index_name] (col_name,...) REFERENCES tbl_name 

Example

CREATE TABLE person (
  p_id varchar PRIMARY KEY,
  name varchar, 
  lastname varchar, 
  age bigint, 
  city varchar, 
  income int, 
  dbl double, 
  dtime datetime
);

Due to multi-model support considerations, if primary key field is not presented, CREATE TABLE automatically creates the primary key id field, as, in the graph or document model, every node or document should have an unique identifier.

Current version limitations:

  • primary key cannot be compound;
  • primary key field must be of varchar type;
  • foreign key references only primary key;
  • respectively, foreign key must be of varchar type too;
  • primary key field value must be unique within the database.

CREATE TABLE AS EDGE

A special table for graph edge representation will be created. Such a table could be considered as an intermediate many-to-many table with two standard fields: fromid and toid. These fields will be added automatically.

Syntax

CREATE TABLE link_name AS EDGE from_tablename to_tablename; 

Example

CREATE TABLE owner AS EDGE car person;

Query example

SELECT p.id, name, lastname, age, c.id, c.model 
FROM person p 
  JOIN owner o ON p.id = o.toid 
  JOIN car c ON c.id = o.fromid 
WHERE age > 20 AND model = 'Toyota' 

The following query gives the same result (see also the JOIN expression description):

SELECT p.id, name, lastname, age, c.id, c.model 
FROM person p 
  JOIN car c ON p.id = c.owner 
WHERE age > 20 AND model = 'Toyota'

ALTER TABLE

Syntax

ALTER TABLE tbl_name
    [alter_specification [, alter_specification] ...]

alter_specification:
  table_options
  | ADD [COLUMN] col_name column_definition,...
  | ADD [COLUMN] (col_name column_definition,...)
  | ADD [CONSTRAINT [symbol]]
        FOREIGN KEY [index_name] (col_name) REFERENCES tbl_name
  | {ALTER|MODIFY} [COLUMN] col_name column_definition,...
  | DROP [COLUMN] col_name


column_definition:
    data_type [NOT NULL | NULL] [DEFAULT literal]

Example

ALTER TABLE person ADD birthday DATE;

CREATE INDEX

Syntax

CREATE [UNIQUE] INDEX index_name ON tbl_name (col_name,...)

Example

CREATE INDEX p_ndx_age ON person (age);

DROP TABLE

Syntax

DROP TABLE [IF EXISTS]
    tbl_name

Example

DROP TABLE person;

DROP INDEX

Syntax

DROP INDEX index_name [ON tbl_name]

Example

DROP INDEX p_ndx_age;

INSERT

Syntax

INSERT [INTO] tbl_name
    [(col_name,...)]
     VALUES (value,...)

Example

INSERT INTO person
     (id, name, lastname, age, city, dbl, dtime)
     VALUES
     ('person5000', 'John', 'Tester', 30, 
     'Lisbon', 1.11, '2018-07-03 01:52:02.65');

BULK INSERT

Syntax

BULK INSERT table_name (col_name,...) 
FROM 'file_path' 
[WITH ([FIRSTROW = number,] [FIELDTERMINATOR = 'character'])]

Example

BULK INSERT person (id, name, lastname, age, city, income, dbl, dtime) 
FROM 'sntest1/person.csv' 
WITH (FIRSTROW = 2, FIELDTERMINATOR = ',');

Note

The FIRSTROW parameter specifies the line number from which the import should be started. For example, one should write FIRSTROW = 2 in order to skip headers.

Filepath is absolute or relative with respect to the directory where the running server file is located. For example, if nbserver.exe file is located in the c:/nitrosbase/bin directory, then the ../data/csv/person.csv path will be expanded as c:/nitrosbase/data/csv/person.csv.

UPDATE

Syntax

UPDATE table_reference
    SET col_name = value,...
    [WHERE where_condition]

UPDATE table_name_or_alias
    SET col_name = value,...
    FROM tablename [alias] | join_expression
    [WHERE where_condition]

Example

UPDATE person SET name = 'LAMAR' WHERE name = 'Lamar'

Note

Syntax of the FROM and WHERE expressions is the same as in the SELECT query.

DELETE

Syntax

DELETE FROM tbl_name
    [WHERE where_condition]
 
DELETE table_name_or_alias FROM join_expression
    [WHERE where_condition]

Example

DELETE FROM person WHERE name = 'Livia'

Note

Syntax of the FROM and WHERE expressions is the same as in the SELECT query.

BACKUP

BACKUP DATABASE TO path

Example

BACKUP DATABASE TO 'c:/data/sntest1/backup'

SELECT

Syntax

SELECT
    [ DISTINCT ]
    select_expression [, select_expression ...]
    FROM tablename | join_expression
    [WHERE where_condition]
    [WHERE INDEX where_condition]
    [GROUP BY col_name [, col_name ...]]
    [HAVING where_condition]
    [ORDER BY col_name [ASC | DESC] [, col_name …] ]
    [LIMIT row_count] 
    [OFFSET offset]

SELECT expression

May contain the following:

  • List of fields:

    SELECT name, lastname FROM person
    
  • All fields:

    SELECT * FROM person
    SELECT p.*, c.model FROM person p JOIN car c ON p.id = c.owner
    
  • AS:

    SELECT count(*) AS countofpersons FROM person
    
  • Simple functions and expressions:

    SELECT UPPER(name) AS uname, age*2 AS dbl FROM person
    
  • Aggregate functions:

    SELECT count(age), min(age), max(age), avg(age) FROM person
    
  • DISTINCT:

    SELECT distinct name, lastname FROM person
    
  • nested SELECT:

    SELECT 
      name, 
      (SELECT model FROM car WHERE p.id = owner) 
        AS modelname 
    FROM person p;
    
  • CASE...WHEN:

    SELECT name, 
      CASE name 
        WHEN 'Lamar' THEN 'L' 
        WHEN 'Mercedez' THEN 'M' 
        ELSE 'U' END AS n
    FROM person;
    
    SELECT id, 
      CASE WHEN age < 30 THEN 1 
      ELSE 2 END as age_category, 
      name, lastname, income
    from person
    

WHERE clause

  • Comparison and logical operators:

    SELECT * FROM person WHERE age > 20 AND name = 'Lamar'
    
  • LIKE operator:

    SELECT * FROM person WHERE name LIKE '%amar%'
    SELECT * FROM person WHERE name LIKE 'L[ai]%'
    
  • IN operator:

    SELECT name, age FROM person 
    WHERE age IN (20, 22, 24) AND name IN ('Lamar', 'Susan')
    
  • NULL check:

    SELECT * FROM person WHERE age IS NULL
    SELECT * FROM person WHERE age IS NOT NULL
    
  • Simple functions and expressions:

    SELECT * FROM person WHERE age*2 - income/20 > 0 AND UPPER(name) = 'LAMAR'
    

FROM and JOIN clauses

Single table query:

SELECT * FROM person 

JOIN operations through FOREIGN-KEY field or EDGE intermediate table are quick. We recommend heavily using such simple JOIN operations when developing the database.

NitrosBase significantly speeds up the processing of such JOIN operations, as it is multi-model and uses graph subsystem features for storing links.

In the relational representation, relationships between objects are represented as links from FOREIGN KEY fields to the id field of a record in the same or different table. The ON condition can only contain the operator =.

  • JOIN between two tables via foreign key:

    SELECT name, model FROM person p JOIN car c ON p.id = c.owner
    
  • JOIN between two tables through an intermediate table (in this example through the table owner having type EDGE intended to describe the graph edges):


SELECT p.id, name, lastname, age, c.id, c.model
FROM person p 
  JOIN owner o ON p.id = o.toid 
  JOIN car c ON c.id = o.fromid
WHERE age > 20 AND model = 'Toyota';

JOIN queries through simple non-FOREIGN-KEY fields are slow and require an index. We recommend to rebuild the database structure to use FOREIGN-KEY for improved performance.

  • JOIN through simple non-FOREIGN-KEY field

    SELECT p1.id, p2.id 
    FROM person p1 
      JOIN person2 p2 
      ON p1.name = p2.name
    

    an index is required to complete such query

    CREATE INDEX p_name ON person (name)
    

    and/or

    CREATE INDEX p2_name ON person2 (name)
    
  • JOIN through several fields with and condition

    SELECT p1.id, p2.id 
    FROM person p1 
      JOIN person2 p2 
      ON p1.name = p2.name AND p1.lastname = p2.lastname
    

    To perform this query it is desirable to create an index on two fields

    CREATE INDEX p_name_lastname ON person (name, lastname)
    

    or (for person2 table)

    CREATE INDEX p2_name_lastname ON person2 (name, lastname)
    

    But it is enough to have one simple index on the field name (or lastname) for the table person (or person2).

    CREATE INDEX p_name ON person (name)  
    CREATE INDEX p_name ON person (lastname)  
    CREATE INDEX p_name ON person2 (name)  
    CREATE INDEX p_name ON person2 (lastname)
    
  • OUTER JOIN
    In current version, OUTER JOIN works only for the links through FOREIGN-KEY fields.

    SELECT p.*, c.model 
    FROM person p 
    LEFT OUTER JOIN car c 
    ON p.id = c.owner AND c.model = 'Honda'
    
    SELECT p.*, c.model 
    FROM person p 
      RIGHT OUTER JOIN car c 
      ON p.id = c.owner AND p.age = 45
    
  • JOIN with the nested query SELECT

    SELECT p.age, p2.age 
    FROM person p 
      JOIN ( SELECT name, lastname, age FROM person ) p2 
      ON p.name = p2.name and p.lastname = p2.lastname
    

GROUP BY clause

  • Grouping by single field:

    SELECT COUNT(dbl), AVG(dbl), MIN(dbl), MAX(dbl) 
    FROM person 
    GROUP BY city;
    
  • Grouping by multiple fields:

    SELECT COUNT(dbl), AVG(dbl), MIN(dbl), MAX(dbl) 
    FROM person 
    GROUP BY city, name;
    
  • Filtering aggregates with HAVING:

    SELECT city, AVG(dbl) AS avg_dbl
    FROM person
    GROUP BY city
    HAVING (avg_dbl <= 0.5);
    

It is possible to use simple functions and DISTINCT in aggregate functions:

SELECT AVG(income*dbl) AS avg_expr FROM person
SELECT AVG( 
  CASE WHEN name = 'Lamar' THEN 1 
       WHEN name = 'Mercedez' THEN 2 
       ELSE 0 end
  ) AS avg_expr  
FROM person'
SELECT city, COUNT(DISTINCT id) FROM person GROUP BY city;
SELECT AVG(income*dbl) AS avg_expr FROM person
SELECT AVG( CASE WHEN name = 'Lamar' THEN 1 WHEN name = 'Mercedez' THEN 2 ELSE 0 END) AS avg_name  
FROM person
SELECT city, COUNT(DISTINCT id) FROM person GROUP BY city

If GROUP BY is omitted, but aggregate functions are present, then the whole result is considered as a single group.

ORDER BY clause

  • Simple sorting by single field:

    SELECT name, lastname, age
    FROM person 
    ORDER BY name
    
  • Sorting by multiple fields with order specified:

    SELECT name, lastname, age
    FROM person
    ORDER BY name, lastname ASC, age DESC
    

LIMIT and OFFSET clauses

LIMIT and OFFSET are used to specify the number of results:

  • First 100 results:

    SELECT * FROM person LIMIT 100
    
  • 10 results starting FROM 100th (i. e., skipping first 100 results, as numbering starts FROM zero):

    SELECT * FROM person LIMIT 10 OFFSET 100
    

Operators

  • comparison operators:

    >, >=, <, <=, =, <>, !=, IS NULL, IS NOT NULL, IN

    SELECT * FROM person WHERE age IS NULL
    
  • LIKE, which matches strings against simple patterns (similar to LIKE in MS SQL Server).
    In addition to regular characters, a pattern may contain wildcards. % denotes any number of subsequent characters; _ denotes any single character; [] is for any single character within a range ([a-z]) or set ([abc]); [^] is for any single character not within a range ([^a-z]) or set ([^abc]). In order to escape special characters, enclose them into [].

  • logical operators:

    and (&&), or (||), not (!)

    SELECT * FROM person
    WHERE age > 50 AND (name = 'Lamar' OR lastname = 'Wurdeman')
    
  • arithmetic operators:

    +, -, *, /

    SELECT age*2 FROM person WHERE age*100/income > 3
    

UNION

Syntax

SELECT ...
UNION [ALL] 
SELECT ...
[UNION [ALL] SELECT ...]

Example

SELECT id, name, lastname, city FROM person WHERE id = 'person22' 
UNION 
SELECT id, name, lastname, city FROM person WHERE id = 'person33' 
UNION 
SELECT id, name, lastname, city FROM person WHERE id = 'person55

FUNCTIONS

Name Description
ABS Returns the absolute value of a number
ACOS Returns the arccosine of a number
ASCII Returns the ASCII value for the specific character
ASIN Returns the arc sine of a number
ATAN Returns the angle, in radians, whose tangent is a specified float expression
CAST Convert a value of any type into a value with a specified type
CEIL, CEILING Returns the smallest integer value that is larger than or equal to a number
CHR Accepts an ASCII code and returns the corresponding character
CONCAT Adds two or more expressions together
COS Returns the cosine of a number
COT Returns the cotangent of a number
DIV Used for integer division (x is divided by y). An integer value is returned
EXP Returns the exponential value of the specified float expression.
LEFT, STRLEFT Returns the left part of a character string with the specified number of characters
LEN, LENGTH Returns the length of a string (in bytes)
LN, LOG Returns the natural logarithm of a number
LOG10 Returns the base-10 logarithm of the specified float expression
LOG2 Returns the base-2 logarithm of a specified value
LOWER Converts a string to lower-case
LPAD Left-pads a string with another string, to a certain length
MOD Function is used to get the remainder from a division
MONTH Return the month part of a date
PI Returns the constant value of Pi
POWER Returns the value of the specified expression to the specified power
POS, POSITION Returns the position of the first occurrence of a substring in a string
RAND Returns a pseudo-random float value from 0 through 1, exclusive.
REPEAT Repeats a string as many times as specified
REPLACE Replaces all occurrences of a substring within a string
REVERSE Reverses a string and returns the result
ROUND Returns a numeric value, rounded to the specified length or precision
YEAR Function returns the year part for a specified date
STRLEFT Extracts a number of characters from a string (starting from left)
STRRIGHT Extracts a number of characters from a string (starting from right)
RPAD Right-pads a string with another string, to a certain length
REGEX Match regex pattern
RIGHT, STRRIGHT Returns the right part of a character string with the specified number of characters
SIGN Returns the sign of a number: -1 for negatives, 0 for 0, 1 for positives
SIN Returns the sine of a number
SQRT Returns the square root of a number
SUBSTR, SUBSTRING Extracts a substring from a string (starting at any position)
TAN Returns the tangent of a number
TRIM Removes leading and trailing spaces from a string
TRUNCATE Truncates a number to the specified number of decimal places
UPPER Converts a string to upper-case

DATA TYPES

Type Pseudonyms Description
BIT BOOL 0 or 1, a boolean data type
INT INTEGER, TINYINT 4-byte integer: from -2 147 483 648 to 2 147 483 647
BIGINT 8-byte integer: from -9 223 372 036 854 775 808 to 9 223 372 036 854 775 807
REAL(s,d) DOUBLE(size,d), FLOAT(size,d) 8-byte floating-point number with scale 1.7E+308 and precision up to 1.7E-308.
Values in round brackets are ignored
DATE Dates from 0001-01-01 (January 1st, 0001) to 9999-12-31 (December 31st, 9999).
Supported string representations:
  • YYYY-MM-DD: 2017-07-31
  • YYYY/MM/DD: 2017/07/31
  • YYYY.MM.DD: 2017.07.31
DATETIME Date and time, where date is in the same interval as in DATE.
Supported string representations:
  • YYYY-MM-DD hh:mm:ss:nnnnnnn: 2017-07-31 01:21:34.1234567
  • YYYY/MM/DD hh:mm:ss:nnnnnnn: 2017/07/31 01:21:34.1234567
  • YYYY.MM.DD hh:mm:ss:nnnnnnn: 2017.07.12 01:21:34.1234567
CHAR(size) VARCHAR(size), TEXT String; value in round brackets is ignored

PSEUDO TABLES

EDGE-TABLES

Table creation:

CREATE TABLE friends AS EDGE person person;

Filling in the table:

INSERT INTO friends VALUES ( 'person22', 'person1022' );
INSERT INTO friends VALUES ( 'person22', 'person1023' );

Data retrieval:

SELECT p1.id, p2.id
  FROM person p1
  JOIN friends f ON p1.id = f.fromid
  JOIN person p2 ON f.toid = p2.id
WHERE p1.id = 'person22';

Alternative simplified method:

SELECT p1.id, p2.id 
  FROM person p1 
  JOIN person p2 ON p1.friends = p2.id 
WHERE p1.id = 'person22';

Updating data:

UPDATE friends EDGES( 'person7', 'person1007' ) SET( 'person7', 'person67' ),
UPDATE friends SET fromid = 'person7', toid = 'person67' 
WHERE fromid = 'person7' AND toid = 'person1007'
UPDATE car SET owner = 'person23' WHERE id = 'car4022',

Short form:

UPDATE friends EDGES('person22', 'person1023' ) SET('person1022', 'person1023');

Alternative simplified method:

UPDATE person SET friends = 'person1023' WHERE id = 'person1022';

Deleting data:

DELETE FROM friends WHERE fromid = 'person22' AND toid = 'person1022';
DELETE FROM owner WHERE toid = 'person22',
DELETE FROM owner WHERE fromid = 'car4021',

Obtaining the list of tables

SELECT * FROM INFORMATION_SCHEMA.TABLES

The result contains two fields:

  • name — table name;
  • type — table type (2 — regular table; 3 — link table, see CREATE TABLE AS EDGE).

Note. C++ API has special function nb_get_tableslist() for getting list of tables.

Obtaining the list of table fields

SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='car'

A result contains five fields:

  • name — field name;
  • type — field type:
    1 — string,
    2 — int,
    3 — bigint,
    4 — double,
    5 — datetime,
    6 — bool,
    7 — date,
    8 — if field is a primary key or a foreign key (and is a string thereafter);
  • subtype — specifies the previous field:
    0 — regular field,
    1 — primary key,
    2 — foreign key;
  • linktable — referenced table name for foreign key;
  • nullable — always TRUE in the current version.

Note. C++ API has special function nb_get_tableschema() for getting list of fields.

USING INDEXES

Index creating

CREATE INDEX p_age ON person (age)  
CREATE INDEX p_name ON person (name)  

Index deleting

DROP INDEX index_name [ON tbl_name]

Using index in simple queries

SELECT * FROM person WHERE age = 22  

This query uses the p_age index

SELECT * FROM person WHERE age = 22 and name = 'Lamar'

In this case, two indexes p_age and p_name are used.

Queries on the range

SELECT * FROM person WHERE age >= 22 and age < 24

Multiple Field Indexes

CREATE INDEX p_name_lastname ON person (name, lastname)  
SELECT * FROM person WHERE name = 'Lamar' and lastname = 'Tanon'

When processing the simple queries the indexes are used when the condition using index selects less than 6% of records.

For simple comparisons it is possible to explicitly require the use of a pre-created index. To do that type INDEX keyword after WHERE keyword:

SELECT name, lastname, city, model 
FROM person p JOIN car c ON c.owner = p.id 
WHERE INDEX name = 'Lamar';

Indexes are also used when processing queries containing a JOIN expression (see section "FROM and JOIN clauses")

SELECT name, lastname, city, model 
FROM person p JOIN car c ON c.owner = p.id 
WHERE INDEX name = 'Lamar';