# Values

## Primitive Types

### String

Character strings encoded in UTF-8.

### Integer

64-bit signed integers.

### Float

64-bit floating point numbers.

### Boolean

Boolean values. true or false.

### Ternary

Values of three-valued logic. TRUE, UNKNOWN or FALSE.

### Datetime

Values of Date and time with nanoseconds.

### Null

Representations of missing values.

NULL is not a state indicating that a value does not exist or UNKNOWN, but a value of a different type from UNKNOWN. Empty cells are set to NULL, and UNKNOWN is used as the results of the operator evaluations.

Note that

`NULL IS UNKNOWN`

evaluates to`TRUE`

, but`UNKNOWN IS NULL`

evaluates to`FALSE`

.

## Expressions that can be used as a value

- Field Reference
- Arithmetic Operation
- String Operation
- Function
- Subquery
- Variable
- Variable Substitution
- Environment Variable
- Runtime Information
- System Defined Constant
- Flag
- Parentheses
- Case Expressions
- Comparison Operation
- Logic Operation
- Cursor Status

### Field Reference

References to fields in tables.

A field reference is represented by a column name or a table name and a column name joined with a full stop(U+002E). Fields can also be referred with column numbers in each table starting with 1.

```
field_reference
: column_name
| table_name.column_name
| table_name.column_number
```

*table_name*- identifier
*column_name*- identifier
*column_number*- integer

### Arithmetic Operation

### String Operation

### Function

- Logical Functions
- Numeric Functions
- DateTime Functions
- String Functions
- Cryptographic Hash Functions
- Cast Functions
- System Functions
- Aggregate Functions
- Analytic Functions
- User Defined Functions

### Subquery

Select Query enclosed in parentheses.

A result set of a subquery must have exactly one field and at most one record. If the result set has no record, that subquery returns null.

### Variable

### Variable Substitution

### Environment Variable

### Runtime Information

### System Defined Constant

### Flag

### Parentheses

Values enclosed in parentheses.

Parentheses are used to specify the order of operations.

### Case Expressions

#### Case syntax with condition

```
CASE
WHEN condition THEN result
[WHEN condition THEN result ...]
[ELSE result]
END
```

*condition*- value
*result*- value

This syntax returns the *result* of the first WHEN expression that *condition* is TRUE.
If no condition is TRUE, then returns the *result* of the ELSE expression or a null if there is no ELSE expression.

#### Case syntax with comparison

```
CASE value
WHEN comparison_value THEN result
[WHEN comparison_value THEN result ...]
[ELSE result]
END
```

*value*- value
*comparison_value*- value
*result*- value

This syntax returns the *result* of the first WHEN expression that *comparison_value* is equal to *value*.
If no *comparison_value* is match, then returns the *result* of the ELSE expression or a null if there is no ELSE expression.

### Comparison Operation

### Logic Operation

### Cursor Status

## Automatic Type Casting

Every Value has a primitive type. A value is converted to another primitive type as necessary. For example, in arithmetic operations, both left-hand side value and right-hand side value are converted to integer or float values. If the conversion fails, then the value is converted to null.

Field values are imported as strings from csv. You can cast value types expressly by using cast functions, and the result is slightly different from an automatic conversion.

Conversion to | Type | Value | Value after conversion |
---|---|---|---|

String | Integer | String representing the decimal integer | |

Float | String representing the floating-point decimal | ||

Datetime | Null | ||

Boolean | Null | ||

Ternary | Null | ||

Null | Null | ||

Integer | String | Representation of a decimal integer | Integer represented by the string |

Other values | Null | ||

Float | Null | ||

Datetime | Null | ||

Boolean | Null | ||

Ternary | Null | ||

Null | Null | ||

Float | String | Representation of a floating-point decimal or its exponential notation | Float represented by the string |

‘Inf’, ‘+Inf’ | +Inf | ||

‘-Inf’ | -Inf | ||

‘NaN’ | NaN | ||

Other values | Null | ||

Integer | Float equivalent to the integer | ||

Datetime | Null | ||

Boolean | Null | ||

Ternary | Null | ||

Null | Null | ||

Datetime | String | Datetime Formats | Datetime represented by the string |

Other values | Null | ||

Integer | Null | ||

Float | Null | ||

Boolean | Null | ||

Ternary | Null | ||

Null | Null | ||

Boolean | String | ‘1’, ‘t’, ‘true’ | true |

‘0’, ‘f’, ‘false’ | false | ||

Other values | Null | ||

Integer | 1 | true | |

0 | false | ||

Other values | Null | ||

Float | 1 | true | |

0 | false | ||

Other values | Null | ||

Datetime | Null | ||

Ternary | TRUE | true | |

FALSE | false | ||

UNKNOWN | Null | ||

Null | Null | ||

Ternary | String | ‘1’, ‘t’, ‘true’ | TRUE |

‘0’, ‘f’, ‘false’ | FALSE | ||

Other values | UNKNOWN | ||

Integer | 1 | TRUE | |

0 | FALSE | ||

Other values | UNKNOWN | ||

Float | 1 | TRUE | |

0 | FALSE | ||

Other values | UNKNOWN | ||

Datetime | UNKNOWN | ||

Boolean | true | TRUE | |

false | FALSE | ||

Null | UNKNOWN |

String formats representing Datetime