fix(structure): keep Oracle case-sensitive identifiers quoted when quoting off

apps/desktop/src/lib/sql/__tests__/ddlDisplay.spec.ts

@@ -142,6 +142,22 @@ describe("omitDdlIdentifierQuotes", () => {
     const ddl = 'ALTER TABLE "SYSTEM"."TEST" RENAME COLUMN "ABCD" TO "AbCd";';
     expect(formatGeneratedDdlIdentifierQuotes(ddl, "oracle", true)).toBe(ddl);
   });
+
+  it("keeps case-sensitive Oracle identifiers quoted when the edited table preserves case (#9649)", () => {
+    const ddl = 'ALTER TABLE "DBX_TEST"."T_9649" MODIFY ("cName" VARCHAR2(120 BYTE));\nALTER TABLE "DBX_TEST"."T_9649" ADD ("cNabcs" clob);\nCOMMENT ON COLUMN "DBX_TEST"."T_9649"."cName" IS \'中文名\';';
+    const expected = 'ALTER TABLE DBX_TEST.T_9649 MODIFY ("cName" VARCHAR2(120 BYTE));\nALTER TABLE DBX_TEST.T_9649 ADD ("cNabcs" clob);\nCOMMENT ON COLUMN DBX_TEST.T_9649."cName" IS \'中文名\';';
+    expect(formatGeneratedDdlIdentifierQuotes(ddl, "oracle", false, { preserveCaseSensitiveIdentifiers: true })).toBe(expected);
+  });
+
+  it("still folds plain Oracle identifiers while preserving case-sensitive ones (#9649)", () => {
+    const ddl = 'ALTER TABLE "SYSTEM"."TEST" ADD ("ID" NUMBER(10), "NEW_COL" VARCHAR2(20), "with space" VARCHAR2(20));';
+    expect(formatGeneratedDdlIdentifierQuotes(ddl, "oracle", false, { preserveCaseSensitiveIdentifiers: true })).toBe('ALTER TABLE SYSTEM.TEST ADD (ID NUMBER(10), NEW_COL VARCHAR2(20), "with space" VARCHAR2(20));');
+  });
+
+  it("ignores the case-preservation option for dialects that keep their own rules", () => {
+    const ddl = 'ALTER TABLE "user_login_log" ADD "status" INT;';
+    expect(formatGeneratedDdlIdentifierQuotes(ddl, "dameng", false, { preserveCaseSensitiveIdentifiers: true })).toBe(ddl);
+  });
 });
 
 describe("ddlFormatDialectFor", () => {

apps/desktop/src/lib/sql/ddlDisplay.ts

@@ -64,25 +64,38 @@ export function omitDdlIdentifierQuotes(sql: string, dialect: SqlFormatDialect):
 
 const SIMPLE_ORACLE_IDENTIFIER = /^[A-Za-z_][A-Za-z0-9_$#]*$/;
 
+export interface GeneratedDdlIdentifierQuoteOptions {
+  /**
+   * Set by structure editors whose edited table already stores a lowercase or
+   * mixed-case identifier. Oracle folds bare identifiers to uppercase, so
+   * unquoting `"cName"` turns the statement into `CNAME` — a different column,
+   * which fails with ORA-00904 or silently creates a differently-cased column.
+   * Preserving the case keeps quotes on every name that would change identity
+   * while plain names keep the folding behaviour requested in #8997.
+   */
+  preserveCaseSensitiveIdentifiers?: boolean;
+}
+
 /**
  * Applies the identifier-quoting preference to SQL generated by a structure
  * editor. Oracle folds bare identifiers to uppercase, so safe quoted names
  * are uppercased before their quotes are removed. Dameng keeps its stricter
  * case-sensitive identifier rules through omitDdlIdentifierQuotes instead.
  */
-export function formatGeneratedDdlIdentifierQuotes(sql: string, dialect: SqlFormatDialect, quoteIdentifiers: boolean): string {
+export function formatGeneratedDdlIdentifierQuotes(sql: string, dialect: SqlFormatDialect, quoteIdentifiers: boolean, options: GeneratedDdlIdentifierQuoteOptions = {}): string {
   if (quoteIdentifiers) return sql;
   if (dialect !== "oracle") return omitDdlIdentifierQuotes(sql, dialect);
 
+  const preserveCaseSensitive = options.preserveCaseSensitiveIdentifiers === true;
   const tokens = tokenizeSqlSemantic(sql, dialect);
   const replacements: Array<{ start: number; end: number; value: string }> = [];
 
   for (const token of tokens) {
     if (token.kind !== "quoted_identifier") continue;
     const identifier = unquoteSqlSemanticIdentifier(token);
-    if (SIMPLE_ORACLE_IDENTIFIER.test(identifier) && !requiresOracleIdentifierQuote(identifier.toUpperCase())) {
-      replacements.push({ start: token.span.start, end: token.span.end, value: identifier.toUpperCase() });
-    }
+    if (!SIMPLE_ORACLE_IDENTIFIER.test(identifier) || requiresOracleIdentifierQuote(identifier.toUpperCase())) continue;
+    if (preserveCaseSensitive && identifier !== identifier.toUpperCase()) continue;
+    replacements.push({ start: token.span.start, end: token.span.end, value: identifier.toUpperCase() });
   }
 
   let result = sql;