问错误:无效正则表达式:在Postgres 11.0中执行左联接时括号()不平衡

EN

atc_code_no code    level   text
1           A       1       ALIMENTARY TRACT AND METABOLISM
2           A01     2       STOMATOLOGICAL PREPARATIONS
3           A01A    3       STOMATOLOGICAL PREPARATIONS
3           A01W    3       (herbal stomatological remedies
4           A01AA   4       Caries prophylactic agents
5           A01AB   4       Antiinfectives and antiseptics for local oral treatment
7           A01AD   4       Other agents for local oral treatment

with level1 as(
        select CONCAT("code", ' (', lower("text"), ')') as atc_code_level1 from s0_atc_code
        where level = '1'
        ),
        
        level2 as(
        select CONCAT("code", ' (', lower("text"), ')') as atc_code_level2 from s0_atc_code
        where level = '2'
        ) ,
        
        level3 as(
        select CONCAT("code", ' (', lower("text"), ')') as atc_code_level3 from s0_atc_code
        where level = '3'
        ) ,
        
        level4 as(
        select CONCAT("code", ' (', lower("text"), ')') as atc_code_level4 from s0_atc_code
        where level = '4'
        )

       SELECT level1.*,
              level2.*,
              level3.*,
              level4.*
              
       FROM level1
       LEFT JOIN level2 ON btrim(SUBSTRING(level2.atc_code_level2, '(.*) \(')) ~ btrim(SUBSTRING(level1.atc_code_level1, '(.*) \('))
       LEFT JOIN level3 ON btrim(SUBSTRING(level3.atc_code_level3, '(.*) \(')) ~ btrim(SUBSTRING(level2.atc_code_level2, '(.*) \('))
       LEFT JOIN level4 ON btrim(SUBSTRING(level4.atc_code_level4, '(.*) \(')) ~ btrim(SUBSTRING(level3.atc_code_level3, '(.*) \('))

atc_code_level1                     atc_code_level2                     atc_code_level3                        atc_code_level4
A (alimentary tract and metabolism) A01 (stomatological preparations)   A01A (stomatological preparations)  A01AD (other agents for local oral treatment)
A (alimentary tract and metabolism) A01 (stomatological preparations)   A01A (herbal stomatological remedies)   A01AA (caries prophylactic agents)
A (alimentary tract and metabolism) A01 (stomatological preparations)   A01A (herbal stomatological remedies)   A01AB (antiinfectives and antiseptics for local oral treatment)