diff --git a/sql/20261110_backfill_college_id.sql b/sql/20261110_backfill_college_id.sql
index 5f50677..2a56f7f 100644
--- a/sql/20261110_backfill_college_id.sql
+++ b/sql/20261110_backfill_college_id.sql
@@ -143,6 +143,9 @@ WHERE t.college_id IS NULL AND t.deleted = 0 AND t.user_id IS NOT NULL;
 --                   这样排除「药学院党委」「护理学院团委」这类手工节点，
 --                   也不用把学校根节点 ID（24）硬编码进脚本。
 --    组织名为空的节点先排除：空名会成为 LIKE '%%' 匹配一切，把每行都变成「多义」。
+--    排序规则：业务表学院列是 utf8mb4_general_ci，sys_organization 在 MySQL 8 上是
+--    utf8mb4_0900_ai_ci，直接 LIKE 会报 Illegal mix of collations，所以显式 COLLATE 到
+--    utf8mb4_general_ci（5.7 与 8.0 都支持，两边方向都能收敛）。
 --    已知误配风险（文本包含关系，故意不猜）：见 DONE 的 notes。
 -- ---------------------------------------------------------------------------
 
@@ -155,7 +158,7 @@ SET college_id = (
       AND o.organization_name <> ''
       AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
             OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-      AND t.unit_name LIKE CONCAT('%', o.organization_name, '%')
+      AND t.unit_name LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%')
 )
 WHERE t.college_id IS NULL AND t.deleted = 0
   AND t.unit_name IS NOT NULL AND t.unit_name <> '';
@@ -169,7 +172,7 @@ SET college_id = (
       AND o.organization_name <> ''
       AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
             OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-      AND t.school_name LIKE CONCAT('%', o.organization_name, '%')
+      AND t.school_name LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%')
 )
 WHERE t.college_id IS NULL AND t.deleted = 0
   AND t.school_name IS NOT NULL AND t.school_name <> '';
@@ -183,7 +186,7 @@ SET college_id = (
       AND o.organization_name <> ''
       AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
             OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-      AND t.school_info LIKE CONCAT('%', o.organization_name, '%')
+      AND t.school_info LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%')
 )
 WHERE t.college_id IS NULL AND t.deleted = 0
   AND t.school_info IS NOT NULL AND t.school_info <> '';
@@ -197,7 +200,7 @@ SET college_id = (
       AND o.organization_name <> ''
       AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
             OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-      AND t.college_grade_class LIKE CONCAT('%', o.organization_name, '%')
+      AND t.college_grade_class LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%')
 )
 WHERE t.college_id IS NULL AND t.deleted = 0
   AND t.college_grade_class IS NOT NULL AND t.college_grade_class <> '';
@@ -324,7 +327,7 @@ SELECT 'gxmu_sjqn' AS module, v.college_text, v.row_count,
           AND o.organization_name <> ''
           AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
                 OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-          AND v.college_text LIKE CONCAT('%', o.organization_name, '%')) AS matched_names
+          AND v.college_text LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%')) AS matched_names
 FROM (SELECT unit_name AS college_text, COUNT(*) AS row_count
       FROM gxmu_sjqn WHERE deleted = 0 AND college_id IS NULL
       GROUP BY unit_name) v
@@ -336,7 +339,7 @@ SELECT 'gxmu_tzbcy_form', v.college_text, v.row_count,
           AND o.organization_name <> ''
           AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
                 OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-          AND v.college_text LIKE CONCAT('%', o.organization_name, '%'))
+          AND v.college_text LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%'))
 FROM (SELECT school_name AS college_text, COUNT(*) AS row_count
       FROM gxmu_tzbcy_form WHERE deleted = 0 AND college_id IS NULL
       GROUP BY school_name) v
@@ -348,7 +351,7 @@ SELECT 'gxmu_qmgc_form', v.college_text, v.row_count,
           AND o.organization_name <> ''
           AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
                 OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-          AND v.college_text LIKE CONCAT('%', o.organization_name, '%'))
+          AND v.college_text LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%'))
 FROM (SELECT school_info AS college_text, COUNT(*) AS row_count
       FROM gxmu_qmgc_form WHERE deleted = 0 AND college_id IS NULL
       GROUP BY school_info) v
@@ -360,7 +363,7 @@ SELECT 'gxmu_wxxzx_project', v.college_text, v.row_count,
           AND o.organization_name <> ''
           AND ( (o.organization_code IS NOT NULL AND o.organization_code <> '')
                 OR EXISTS (SELECT 1 FROM gxmu_student s WHERE s.deleted = 0 AND s.college_id = o.organization_id) )
-          AND v.college_text LIKE CONCAT('%', o.organization_name, '%'))
+          AND v.college_text LIKE CONCAT('%', o.organization_name COLLATE utf8mb4_general_ci, '%'))
 FROM (SELECT college_grade_class AS college_text, COUNT(*) AS row_count
       FROM gxmu_wxxzx_project WHERE deleted = 0 AND college_id IS NULL
       GROUP BY college_grade_class) v;