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Type conversion functions

This topic describes the type conversion functions supported by NebulaGraph.

toBoolean()

toBoolean() converts a string value to a boolean value.

Syntax: toBoolean(<value>)

  • Result type: Bool

Example:

nebula> UNWIND [true, false, 'true', 'false', NULL] AS b \
        RETURN toBoolean(b) AS b;
+----------+
| b        |
+----------+
| true     |
| false    |
| true     |
| false    |
| __NULL__ |
+----------+

toFloat()

toFloat() converts an integer or string value to a floating point number.

Syntax: toFloat(<value>)

  • Result type: Float

Example:

nebula> RETURN toFloat(1), toFloat('1.3'), toFloat('1e3'), toFloat('not a number');
+------------+----------------+----------------+-------------------------+
| toFloat(1) | toFloat("1.3") | toFloat("1e3") | toFloat("not a number") |
+------------+----------------+----------------+-------------------------+
| 1.0        | 1.3            | 1000.0         | __NULL__                |
+------------+----------------+----------------+-------------------------+

toString()

toString() converts non-compound types of data, such as numbers, booleans, and so on, to strings.

Syntax: toString(<value>)

  • Result type: String

Example:

nebula> RETURN toString(9669) AS int2str, toString(null) AS null2str;
+---------+----------+
| int2str | null2str |
+---------+----------+
| "9669"  | __NULL__ |
+---------+----------+

toInteger()

toInteger() converts a floating point or string value to an integer value.

Syntax: toInteger(<value>)

  • Result type: Int

Example:

nebula> RETURN toInteger(1), toInteger('1'), toInteger('1e3'), toInteger('not a number');
+--------------+----------------+------------------+---------------------------+
| toInteger(1) | toInteger("1") | toInteger("1e3") | toInteger("not a number") |
+--------------+----------------+------------------+---------------------------+
| 1            | 1              | 1000             | __NULL__                  |
+--------------+----------------+------------------+---------------------------+

toSet()

toSet() converts a list or set value to a set value.

Syntax: toSet(<value>)

  • Result type: Set

Example:

nebula> RETURN toSet(list[1,2,3,1,2]) AS list2set;
+-----------+
| list2set  |
+-----------+
| {3, 1, 2} |
+-----------+

hash()

hash() returns the hash value of the argument. The argument can be a number, a string, a list, a boolean, null, or an expression that evaluates to a value of the preceding data types.

The source code of the hash() function (MurmurHash2), seed (0xc70f6907UL), and other parameters can be found in MurmurHash2.h.

For Java, the hash function operates as follows.

MurmurHash2.hash64("to_be_hashed".getBytes(),"to_be_hashed".getBytes().length, 0xc70f6907)

Syntax: hash(<string>)

  • Result type: Int

Example:

nebula> RETURN hash("abcde");
+--------------------+
| hash("abcde")      |
+--------------------+
| 811036730794841393 |
+--------------------+
nebula> YIELD hash([1,2,3]);
+----------------+
| hash([1,2,3])  |
+----------------+
| 11093822460243 |
+----------------+
nebula> YIELD hash(NULL);
+------------+
| hash(NULL) |
+------------+
| -1         |
+------------+
nebula> YIELD hash(toLower("HELLO NEBULA"));
+-------------------------------+
| hash(toLower("HELLO NEBULA")) |
+-------------------------------+
| -8481157362655072082          |
+-------------------------------+

Last update: December 8, 2022