i18n(ja): standardize SQL statement H1 headings to English and fix unnatural translations

[yahonda]

What is changed, added or deleted? (Required)

Fix unnatural Japanese translations, standardize terminology, and clean up broken link formats across the i18n-ja docs. Changes are organized by category below.

1. Time to Live translations

Three related literal/unnatural translations of "Time to Live" are fixed:

• 生きる時間 → 存続時間 (4 files): "Time to Live" was literally translated as "生きる時間" (living time). Changed to "存続時間" (lifetime/duration), which is the standard term used in the time-to-live.md page itself.

  Affected: basic-features.md, TOC.md, tidb-cloud/releases/release-notes-2024.md, develop/dev-guide-delete-data.md

• 生きる時が来た → 存続時間（TTL） (4 occurrences in system-variables.md): A different broken phrasing where "時が来た" (time has come) was used in TTL link text. Replaced with the canonical Japanese name "存続時間（TTL）".

2. リテラル値 (Literal values)

• 文字通りの値 → リテラル値 (5 files): "Literal values" was translated as "文字通りの値" (literal/word-for-word value). Changed to "リテラル値", which is the standard programming term (カタカナ) used in the literal-values.md page summary itself.

  Affected: TOC.md, TOC-tidb-cloud.md, TOC-tidb-cloud-starter.md, TOC-tidb-cloud-premium.md, TOC-tidb-cloud-essential.md

3. Collation (照合) terminology

• 照合 → 照合順序 (4 TOC files + basic-features.md): "照合" alone is ambiguous. The full term "照合順序" (collation order) is more precise and matches the standard MySQL terminology.

4. SQL type name consistency

• JSONタイプ → JSON型, ベクトルタイプ → ベクトル型 (basic-features.md): Standardized the suffix from タイプ (katakana) to 型 (kanji) for consistency with the rest of the document.

5. Invisible index terminology (非表示 → 不可視)

The MySQL term "invisible index" is being standardized to use 不可視 (invisible) rather than 非表示 (hidden) for accuracy. "Invisible" is the established MySQL term, and the EN source uses "invisible".

• 非表示 → 不可視 (best-practices/index-management-best-practices.md): Standardized in prose.
• 見えないインデックス → 不可視インデックス (basic-features.md, best-practices/index-management-best-practices.md): Standardized in feature tables and link texts.
• 目に見えないインデックス → 不可視インデックス (sql-statement-create-index.md): Same fix in another file.

6. Expression index translation

• 表現インデックス → 式インデックス (sql-statement-create-index.md): "式インデックス" is the established translation in MySQL documentation.

7. SQL statement H1 headings to English

Many SQL statement page titles were translated into Japanese (e.g., "テーブルを作成" for CREATE TABLE). Standardized to use the English statement name (e.g., CREATE TABLE), matching the EN source and the toc.md file paths. ~80 files updated.

Affected: all sql-statements/sql-statement-*.md files plus toc.md.

8. Section heading consistency

• あらすじ → 概要 (~35 sql-statement files): The "あらすじ" (synopsis) heading is replaced with the more standard "概要" (overview) which is used elsewhere in the docs.
• 関連項目 → 参照 (sql-statement-overview.md and related): "関連項目" (related items) standardized to "参照" (see also) for consistency.
• ステートメントを表示する → SHOW ステートメント (multiple sql-statement files): The heading text was changed to follow the same English-prefix pattern used by other section headings in those files.

9. SQL statement terminology

• 消去 → DELETE (delete-related docs): "消去" (erase) is replaced with the English statement name "DELETE" to match the EN source and avoid confusion with DROP or other operations.
• ロック解除統計 → UNLOCK STATS (unlock-stats docs): "ロック解除統計" was a poor Japanese translation; the English form "UNLOCK STATS" is used, matching the EN source.
• LOCK TABLES and UNLOCK TABLES → LOCK TABLES と UNLOCK TABLES (lock-tables-and-unlock-tables.md): Standardized the conjunction form.

10. Other prose cleanups

• インデックスストレージの中断はゼロ → インデックスストレージへの影響はゼロ (index-management-best-practices.md): The original "中断" (interruption) was a mistranslation; "影響" (impact) is correct.
• 消費者 → コンシューマー, 透かし → WATERMARK, ブートストラップ → BOOTSTRAP (tiflash docs): Standardized terminology to use the canonical terms used elsewhere in the docs.
• IS_VISIBLE description fix (sql-statement-create-index.md): Fixed a misleading description.
• あ → 文 orphan patterns removed (multiple sql-statement files): Removed orphan 文 characters that were left over from broken edits.

11. Broken link formats

• VEC_COSINE_DISTANCE()() → VEC_COSINE_DISTANCE() (ai/integrations/vector-search-auto-embedding-overview.md): The link text had an extra pair of parentheses from a botched edit.
• 表示 ユーザーの作成 → [ユーザーの作成を表示] (sql-statement-show-create-user.md): Fixed a link that was missing the surrounding brackets.
• [グローバル|セッション] バインディング → [[グローバル|セッション]バインディングの作成] (create-binding.md and others): Added the missing outer brackets to make the bracketed-group section name a proper link.
• Link text vs. anchor mismatches (multiple files): Adjusted the displayed link text to match the actual section anchor name to avoid broken anchors.

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

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[gemini-code-assist]

Code Review

This pull request updates Japanese terminology across several documentation files, changing "文字通りの値" to "リテラル値" (literal values) and "生きる時間" to "存続時間" (TTL). The review feedback suggests adding a grammatical particle between adjacent markdown links in the release notes to improve readability, and replacing the non-standard term "消去" with the standard SQL keyword "DELETE" for technical accuracy.

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-06-29 10:43:33.462817636 +0000 UTC m=+36155.163197039: ☑️ agreed by qiancai.

[qiancai]

@yahonda Would you please resolve conflicts in this PR? Thanks.