system.unicode

system.unicode 表是一个虚拟表，用于提供关于 Unicode 字符及其属性的信息（https://unicode-org.github.io/icu/userguide/strings/properties.html）。该表是动态生成的。

Columns

注意

ICU 文档中 Unicode 码点的属性名称会被转换为 snake_case。

• code_point (String) — 码点的 UTF-8 表示。
• code_point_value (Int32) — 码点的数值。
• notation (String) — 码点的 Unicode 表示形式。
• Binary Properties (UInt8) - 码点的二值属性。
  • alphabetic, ascii_hex_digit, case_ignorable...
• Enumerated Properties (Int32) - 码点的枚举属性。
  • bidi_class, bidi_paired_bracket_type, block...
• String Properties (String) - 码点的字符串属性（ASCII 字符串、Unicode 字符串或码点）
  • case_folding, decomposition_mapping, name...

注意

映射规则有一些特殊之处，详见 ICU 文档。例如，simple_uppercase_mapping 和 uppercase_mapping 并不完全相同。但未实现任何与语言相关的映射（例如在土耳其语中，i 的大写是 "İ" (U+0130)）。

• numeric_value (Float64) - 码点的数值。
• script_extensions (Array(LowCardinality(String))) - 码点的书写系统扩展（script extensions）。
• identifier_type (Array(LowCardinality(String))) - 码点的标识符类型。
• general_category_mask (Int32) - 码点的一般类别掩码。

示例

SELECT * FROM system.unicode WHERE code_point = 'a' LIMIT 1;

Row 1:
──────
code_point:                      a
code_point_value:                97
notation:                        U+0061
alphabetic:                      1
ascii_hex_digit:                 1
bidi_control:                    0
bidi_mirrored:                   0
dash:                            0
default_ignorable_code_point:    0
deprecated:                      0
diacritic:                       0
extender:                        0
full_composition_exclusion:      0
grapheme_base:                   1
grapheme_extend:                 0
grapheme_link:                   0
hex_digit:                       1
hyphen:                          0
id_continue:                     1
id_start:                        1
ideographic:                     0
ids_binary_operator:             0
ids_trinary_operator:            0
join_control:                    0
logical_order_exception:         0
lowercase:                       1
math:                            0
noncharacter_code_point:         0
quotation_mark:                  0
radical:                         0
soft_dotted:                     0
terminal_punctuation:            0
unified_ideograph:               0
uppercase:                       0
white_space:                     0
xid_continue:                    1
xid_start:                       1
case_sensitive:                  1
sentence_terminal:               0
variation_selector:              0
nfd_inert:                       1
nfkd_inert:                      1
nfc_inert:                       0
nfkc_inert:                      0
segment_starter:                 1
pattern_syntax:                  0
pattern_white_space:             0
alnum:                           1
blank:                           0
graph:                           1
print:                           1
xdigit:                          1
cased:                           1
case_ignorable:                  0
changes_when_lowercased:         0
changes_when_uppercased:         1
changes_when_titlecased:         1
changes_when_casefolded:         0
changes_when_casemapped:         1
changes_when_nfkc_casefolded:    0
emoji:                           0
emoji_presentation:              0
emoji_modifier:                  0
emoji_modifier_base:             0
emoji_component:                 0
regional_indicator:              0
prepended_concatenation_mark:    0
extended_pictographic:           0
basic_emoji:                     0
emoji_keycap_sequence:           0
rgi_emoji_modifier_sequence:     0
rgi_emoji_flag_sequence:         0
rgi_emoji_tag_sequence:          0
rgi_emoji_zwj_sequence:          0
rgi_emoji:                       0
ids_unary_operator:              0
id_compat_math_start:            0
id_compat_math_continue:         0
bidi_class:                      0
block:                           1
canonical_combining_class:       0
decomposition_type:              0
east_asian_width:                4
general_category:                2
joining_group:                   0
joining_type:                    0
line_break:                      2
numeric_type:                    0
script:                          25
hangul_syllable_type:            0
nfd_quick_check:                 1
nfkd_quick_check:                1
nfc_quick_check:                 1
nfkc_quick_check:                1
lead_canonical_combining_class:  0
trail_canonical_combining_class: 0
grapheme_cluster_break:          0
sentence_break:                  4
word_break:                      1
bidi_paired_bracket_type:        0
indic_positional_category:       0
indic_syllabic_category:         0
vertical_orientation:            0
identifier_status:               1
general_category_mask:           4
numeric_value:                   0
age:                             1.1
bidi_mirroring_glyph:            a
case_folding:                    a
lowercase_mapping:               a
name:                            LATIN SMALL LETTER A
simple_case_folding:             a
simple_lowercase_mapping:        a
simple_titlecase_mapping:        A
simple_uppercase_mapping:        A
titlecase_mapping:               A
uppercase_mapping:               A
bidi_paired_bracket:             a
script_extensions:               ['Latin']
identifier_type:                 ['Recommended']

SELECT code_point, code_point_value, notation FROM system.unicode WHERE code_point = '😂';

   ┌─code_point─┬─code_point_value─┬─notation─┐
1. │ 😂          │           128514 │ U+1F602  │
   └────────────┴──────────────────┴──────────┘